Antisense antiviral compound and method for treating influenza viral infection

ABSTRACT

The present invention relates to antisense antiviral compounds and methods of their use and production in inhibition of growth of viruses of the Orthomyxoviridae family and in the treatment of a viral infection. The compounds are particularly useful in the treatment of influenza virus infection in a mammal. Exemplary antisense antiviral compounds are substantially uncharged, or partially positively charged, morpholino oligonucleotides having 1) a nuclease resistant backbone, 2) 12-40 nucleotide bases, and 3) a targeting sequence of at least 12 bases in length that hybridizes to a target region selected from the following: a) the 5′ or 3′ terminal 25 bases of the negative sense viral RNA segment of Influenzavirus A, Influenzavirus B and Influenzavirus C; b) the terminal 30 bases of the 5′ or 3′ terminus of the positive sense vcRNA; c) the 45 bases surrounding the AUG start codon of an influenza viral mRNA and; d) 50 bases surrounding the splice donor or acceptor sites of influenza mRNAs subject to alternative splicing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 61/261,278, filed Nov. 13, 2009; U.S. Provisional Patent Application No. 61/292,056, filed Jan. 4, 2010; and U.S. Provisional Patent Application No. 61/377,382, filed Aug. 26, 2010, each of which is incorporated by reference in its entirety.

STATEMENT OF GOVERNMENT INTEREST

The invention was made with Government support under HDTRA1-09-C-0046 and HDTRA1-C-10-0079 awarded by Department of Defense. The Government has certain rights in the invention.

STATEMENT REGARDING SEQUENCE LISTING

The Sequence Listing associated with this application is provided in text format in lieu of a paper copy, and is hereby incorporated by reference into the specification. The name of the text file containing the Sequence Listing is 120178_(—)456_SEQUENCE_LISTING.txt. The text file is 33 KB, was created on Nov. 11, 2010, and is being submitted electronically via EFS-Web.

FIELD OF THE INVENTION

The invention relates to antisense oligonucleotides for use in treating an influenza virus infection and antiviral treatment methods employing the oligonucleotides.

BACKGROUND OF THE INVENTION

Influenza viruses have been a major cause of human mortality and morbidity throughout recorded history. Influenza A virus infection causes millions of cases of severe illness and as many as 500,000 deaths each year worldwide. Epidemics vary widely in severity but occur at regular intervals and always cause significant mortality and morbidity, most frequently in the elderly population. Although vaccines against matched influenza strains can prevent illness in 60-80% of healthy adults, the rate of protection is much lower in high-risk groups. Furthermore, vaccination does not provide protection against unexpected strains, such as the H5 and H7 avian influenza outbreaks in Hong Kong in 1997 and Europe and Southeast Asia in 2003 and 2004. Current anti-influenza drugs are limited in their capacity to provide protection and therapeutic effect (Cox and Subbarao 1999; Cox and Subbarao 2000).

Influenza A is a segmented RNA virus of negative-polarity. Genome segments are replicated by a complex of 4 proteins: the 3 polymerase polypeptides (PA, PB1 and PB2) and NP (Nucleoprotein). The 5′ and 3′ terminal sequence regions of all 8 genome segments are highly conserved within a genotype (Strauss and Strauss 2002).

Influenza A viruses can be subtyped according to the antigenic and genetic nature of their surface glycoproteins; 15 hemagglutinin (HA) and 9 neuraminidase (NA) subtypes have been identified to date. Viruses bearing all known HA and NA subtypes have been isolated from avian hosts, but only viruses of the H1N1 (1918), H2N2 (1957/58), and H3N2 (1968) subtypes have been associated with widespread epidemics in humans (Strauss and Strauss 2002).

Since 1997, when H5N1 influenza virus was transmitted to humans and killed 6 of 18 infected persons, there have been multiple transmissions of avian influenza viruses to mammals. Either the whole virus is transmitted directly or gene segments from the avian influenza virus are acquired by mammalian strains. Widespread infections of poultry with H5N1 viruses in Asia have caused increasing concern that this subtype may achieve human-to-human spread and establish interspecies transmission. The species which different types of influenza viruses are able to infect are determined by different forms of the virus glycoproteins (HA, NA). This provides a considerable species barrier between birds and humans which is not easily overcome. Pigs, however, provide a “mixing pot”—able to be infected by both types of virus and thereby allowing the passage of avian viruses to humans. When an individual pig cell is co-infected with both avian and human influenza viruses, recombinant forms can emerge that carry an avian HA genotype but readily infect humans. Avian HA can infect pigs, but not humans. In pigs, during genome segment packaging, it is possible to create a virus with several Avian segments and Human HA and/or NA segments (Cox and Subbarao 2000).

Influenza viruses infect humans and animals (e.g., pigs, birds, horses) and may cause acute respiratory disease. There have been numerous attempts to produce vaccines effective against influenza virus. None, however, have been completely successful, particularly on a long-term basis. This may be due, at least in part, to the segmented characteristic of the influenza virus genome, which makes it possible, through re-assortment of the segments, for numerous forms to exist. For example, it has been suggested that there could be an interchange of RNA segments between animal and human influenza viruses, which would result in the introduction of new antigenic subtypes into both populations. Thus, a long-term vaccination approach has failed, due to the emergence of new subtypes (antigenic “shift”). In addition, the surface proteins of the virus, hemagglutinin and neuraminidase, constantly undergo minor antigenic changes (antigenic “drift”). This high degree of variation explains why specific immunity developed against a particular influenza virus does not establish protection against new variants. Hence, alternative antiviral strategies are needed. Although influenza B and C viruses cause less clinical disease than the A types, new antiviral drugs should also be helpful in curbing infections caused by these agents.

Influenza viruses that occur naturally among birds are called avian influenza (bird flu). The birds carry the viruses in their intestines but do not generally get sick from the infection. However, migratory birds can carry the bird flu to infect domestic chickens, ducks and turkeys causing illness and even death. Avian flu does not easily infect humans but when human exposure is more frequent, such as contact with domestic birds, human infections occur. A dangerous bird flu (H5N1) was first identified in terms in South Africa in 1961 and was identified as a potentially deadly form of flu. Outbreaks of H5N1 occurred in eight Asian countries in late 2003 and 2004. At that time more than 100 million birds in these countries either died or were killed in order to control the outbreak. Beginning in June of 2004 new deadly outbreaks of H5N1 were reported in Asia which are currently ongoing. Human infections of H5N1 have been observed in Thailand, Vietnam and Cambodia with a death rate of about 50 percent. These infections have mostly occurred from human contact with infected poultry but a few cases of human-to-human spread of H5N1 have occurred.

A triple-reassortant influenza A (H1) virus has been circulating since 1998 with segments from pigs (HA, NP, NA, M and NS), humans (PB1), and birds (PB2 and PA). The newly described and novel swine-origin influenza A (2009H1N1) virus (S-OIV), which is responsible for an ongoing international disease outbreak, is a triple reassortant virus that includes genetic elements of this preexisting virus that have reassorted with the neuraminidase (NA) and matrix (M) segments of a Eurasian swine virus (ω-OIV Investigation Team, 2009). The previous influenza A (H1) triple-reassortant virus was occasionally transmitted to humans but not spread efficiently from human-to-human but the new S-OIV is very efficient in human-to-human transmission. Recently, 3440 laboratory confirmed cases of S-OIV infection have been reported from 29 countries. The outbreak began in Mexico, where a total of 1364 cases have been documented, resulting in 45 deaths (case-fatality rate of 3.3%). Outside of Mexico, there have been only three reported deaths (case-fatality rate of 0.1%). The reason for this geographic imbalance in death rate is not clear at this time.

While the S-OIV is currently sensitive to the neuraminidase inhibitors oseltamivir and zanamivir, seasonal influenza has previously been documented to evolve mutations that confer neuraminidase inhibitor resistance. Will S-OIV replace the human H1 as the seasonal influenza virus or will S-OIV reassort with yet another strain of influenza to create another new variant? Will it evolve to become more lethal? These uncertainties are compounded by the time interval from the identification of a new virus to the manufacture and distribution of a new vaccine. Further, a sufficiently novel viral hemagglutinin antigen may necessitate the use of large doses of immunogen and a prime boost schedule, posing practical difficulties for mass vaccination campaigns that must promptly elicit protective immunity. In view of these considerations, there exists an urgent need to create novel forms of prophylaxis and therapy for S-OIV in particular, ideally with broad activity against various influenza viral strains, subtypes and types.

An urgent need exists for new forms of treatment for influenza A based on (a) the known propensity of this virus to undergo both continuous low-level antigenic drift and less frequent but unpredictable major antigenic shift leading to pandemic disease, (b) the clear failure of vaccination, even when strains are reasonably matched, to prevent influenza-related illness in a significant proportion of vaccine recipients, and (c) the increased frequency of resistance to approved forms of therapy for influenza (e.g., the adamantane derivatives and, more recently, the neuraminidase inhibitor, oseltamivir).

In view of the severity of the diseases caused by influenza viruses there is an immediate need for new therapies to treat influenza infection. Given the lack of effective prevention or therapies, it is therefore an object of the present invention to provide therapeutic compounds and methods for treating a host infected with an influenza virus.

BRIEF SUMMARY

Embodiments of the present invention include, in one aspect, an anti-viral compound effective in inhibiting replication within a host cell of an RNA virus having a single-stranded, negative sense genome and selected from the Orthomyxoviridae family including the Influenzavirus A, Influenzavirus B and Influenzavirus C genera. The compound may target viral RNA sequences within a region selected from the following: 1) the 5′ or 3′ terminal 25 bases of the negative sense viral RNA segments; 2) the terminal 25 bases of the 5′ or 3′ terminus of the positive sense cRNA; 3) 45 bases surrounding the AUG start codons of influenza viral mRNAs and; 4) 50 bases surrounding the splice donor or acceptor sites of influenza mRNAs subject to alternative splicing.

In certain embodiments, the antiviral compound may include an oligonucleotide characterized by: a) a nuclease-resistant backbone, b) 12-40 nucleotide bases, and c) a targeting sequence of at least 10 bases in length, that hybridizes to a target region selected from the following: i) the 5′ or 3′ terminal 25 bases of a negative sense viral RNA segment of Influenzavirus A, Influenzavirus B and Influenzavirus C, such as a segment that comprises M1 or M2, ii) the terminal 25 bases of the 5′ or 3′ terminus of a positive sense cRNA of Influenzavirus A, Influenzavirus B and Influenzavirus C, iii) the 45 bases surrounding the AUG start codon of an influenza viral mRNA, such as an M1 or M2 mRNA, and iv) 50 bases surrounding the splice donor or acceptor sites of Influenzavirus A, Influenzavirus B and Influenzavirus C mRNAs subject to alternative splicing, such as an M1 or M2 mRNA.

An oligonucleotide may also be characterized by: a) the capability of being actively taken up by mammalian host cells, and/or b) the ability to form a heteroduplex structure with the viral target region, wherein said heteroduplex structure is: i) composed of the positive or negative sense strand of the virus and the oligonucleotide compound, and ii) characterized by a Tm of dissociation of at least 45° C.

Embodiments of the present invention include, in another aspect, an antiviral compound that inhibits, in a mammalian host cell, replication of an infecting influenza virus having a single-stranded, segmented, negative-sense genome and selected from the Orthomyxoviridae family. The compound may be administered to the infected host cells as an oligonucleotide characterized by the elements described above. The compound may be administered to a mammalian subject infected with the influenza virus, or at risk of infection with the influenza virus.

The compound may be composed of morpholino subunits linked by uncharged, phosphorus-containing intersubunit linkages, joining a morpholino nitrogen of one subunit to a 5′ exocyclic carbon of an adjacent subunit. In one embodiment, the intersubunit linkages are phosphorodiamidate linkages, such as those having the structure:

where Y₁═O, Z═O, Pj is a purine or pyrimidine or an equivalent base-pairing moiety effective to bind, by base-specific hydrogen bonding, to a base in a polynucleotide, and X is alkyl, alkoxy, thioalkoxy, or alkyl amino, e.g., wherein X═NR₂, where each R is independently hydrogen or methyl.

The compound may be composed of morpholino subunits linked with the uncharged linkages described above interspersed with linkages that are positively charged. The total number of positively charged linkages is between 2 and no more than half of the total number of linkages. The positively charged linkages have the structure above, where X is 1-piperazine.

The compound may include a covalent conjugate of an oligonucleotide analog moiety capable of forming such a heteroduplex structure with the positive or negative sense RNA strand of the virus, and an arginine-rich polypeptide effective to enhance the uptake of the compound into host cells. Exemplary polypeptides comprise one of the sequences identified as SEQ ID NOs:115-128.

In a related aspect, embodiments of the present invention include a heteroduplex complex formed between:

-   -   (a) the 5′ or 3′ terminal 25 bases of the negative sense viral         RNA and/or;     -   (b) the terminal 25 bases of the 5′ or 3′ terminus of the         positive sense mRNA and/or;     -   (c) 45 bases surrounding the AUG start codon of viral mRNA         and/or;     -   (d) 50 bases surrounding the splice donor or acceptor sites of         influenza mRNAs subject to alternative splicing and;     -   (e) an oligonucleotide characterized by:         -   (i) a nuclease-resistant backbone,         -   (ii) capable of uptake by mammalian host cells,         -   (iii) containing between 12-40 nucleotide bases,

where said heteroduplex complex has a Tm of dissociation of at least 45° C.

In certain embodiments, an exemplary oligonucleotide may be composed of morpholino subunits linked by uncharged, phosphorus-containing intersubunit linkages, joining a morpholino nitrogen of one subunit to a 5′ exocyclic carbon of an adjacent subunit. The compound may have phosphorodiamidate linkages, such as in the structure

where Y₁═O, Z═O, Pj is a purine or pyrimidine base-pairing moiety effective to bind, by base-specific hydrogen bonding, to a base in a polynucleotide, and X is alkyl, alkoxy, thioalkoxy, or alkyl amino. In a preferred compound, X═NR₂, where each R is independently hydrogen or methyl. The compound may also be composed of morpholino subunits linked with the uncharged linkages described above interspersed with linkages that are positively charged. The total number of positively charged linkages is between 2 and no more than half of the total number of linkages. The positively charged linkages have the structure above, where X is 1-piperazine.

The compound may be the oligonucleotide alone or a conjugate of the oligonucleotide and an arginine-rich polypeptide capable of enhancing the uptake of the compound into host cells. Exemplary polypeptides have one of the sequences identified as SEQ ID NOs:115-128.

In still another aspect, embodiments of the present invention include an antisense oligonucleotide and related methods inhibiting replication in mammalian host cells of an influenza virus having a single-stranded, segmented, negative-sense RNA genome and selected from the Orthomyxoviridae family. The compound may be characterized by the viral RNA elements described herein. In certain embodiments, the cell is in a subject, typically a subject having an influenza-virus infection.

In some embodiments, the subject has a secondary bacterial infection, and the method further comprises administering a bacterial antibiotic, separately or concurrently with the antiviral antisense oligonucleotide. In specific embodiments, the secondary bacterial infection is a Streptococcal pneumonia infection (e.g., Streptococcus pneuomoniae). In certain embodiments, the antibiotic is a beta-lactam. In specific embodiments, the antibiotic is selected from penicillin, amoxicillin, cephalosporins, chloramphenicol, and clindamycin.

Also included are methods of reducing replication of an influenza virus, comprising administering an antisense oligonucleotide targeted against an RNA molecule encoding CD200 or the CD200 receptor, separately or concurrently with one or more antiviral antisense oligonucleotides described herein.

A pharmaceutical composition comprising an antiviral antisense oligonucleotide described herein, and a pharmaceutically acceptable carrier. In some embodiments, the pharmaceutical composition further comprises a bacterial antibiotic, such as penicillin, amoxicillin, cephalosporins, chloramphenicol, or clindamycin. In preferred embodiments, the bacterial antibiotic is bacteriostatic. In some embodiments, the pharmaceutical composition further comprises an antisense oligonucleotide targeted against an RNA molecule encoding CD200 or the CD200 receptor.

For treatment of Influenza virus, such as Influenza A virus, the targeting sequence may hybridize to a region associated with one of the group of sequences identified as SEQ ID NOs:1-11. Preferred targeting sequences are those complementary to either the minus strand target of SEQ ID NO:4 or the positive-strand target of SEQ ID NO:2. Exemplary antisense phosphorodiamidate morpholino oligomers (“PMOs”) that target these two regions are listed as SEQ ID NOs:23 and 12, respectively.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A shows an exemplary morpholino oligomer structure with a phosphorodiamidate linkage;

FIG. 1B shows a morpholino oligomer as in FIG. 1A, but where the backbone linkages contain one positively charged group in the form of a (piperazino) phosphorodiamidate linkage;

FIG. 1C shows a conjugate of an arginine-rich peptide and an antisense oligomer, in accordance with one embodiment of the invention;

FIGS. 1D-G show the repeating subunit segment of exemplary morpholino oligonucleotides, designated D through G.

FIG. 2 shows the structure of a preferred exemplary antisense compound of the invention in a PMOplus™ form (M1/M2-AUGplus; SEQ ID NO: 13). The three (piperazino) phosphorodiamidate (pip-PDA) linkages impart a net positive charge, hence the term PMOplus™.

FIG. 3 shows the three different species of influenza virus RNA present in infected cells, vRNA, mRNA and vcRNA, and the target location of targeting PMO described herein.

FIG. 4A shows the sequence conservation of the 5′ terminal 60 nucleotides of the M1/M2 segment from important serotypes of influenza: H1N1, H1N1(S-OIV), H5N1, H3N2, H9N2 and H7N7.

FIG. 4B shows the percentage of isolates having the indicated base as the subscript number after each base for the M1/M2-AUG target (SEQ ID NO:12)

FIGS. 5A-5B show the location of targeting sequences of the invention relative to the AUG start codon and the 5′ terminus of the vcRNA, respectively.

FIG. 6 shows a dose dependent reduction in viral titer using the M1/M2-AUG targeting compounds of the invention (SEQ ID NOs:12 and 13) in a H3N2 murine model system.

FIGS. 7A-7D show M1/M2-AUG-treated ferrets (SEQ ID NOs: 12 and 13) have reduced in-life clinical signs of flu after infection with a 2009H1N1 (S-OIV) pandemic swine flu isolate.

FIG. 7E shows ferrets infected with S-OIV and treated with the M1/M2-AUG compounds of the invention (SEQ ID NOs: 12 and 13) led to a 2.3 log inhibition of viral titer.

FIGS. 8A-C show the effect of PPMO targeted to the splice acceptor site on viral HA RNA, M1 protein and M2 protein expression, respectively.

FIGS. 9A-B show the effect of antisense LNA oligomers targeted to the M1/M2 AUG start codon on viral HA RNA and M2 protein expression.

FIGS. 10A-B show the effect of antisense 2′OMe oligomers targeted to the M1/M2 AUG start codon and splice acceptor site on viral HA RNA and M2 protein expression.

FIG. 11 shows the inhibition of M1 and M2 protein expression in H1N1 PR8-infected MDCK cells treated with a PPMO targeted to the M1/M2 AUG start codon.

DETAILED DESCRIPTION Definitions

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, preferred methods and materials are described. For the purposes of the present invention, the following terms are defined below.

The articles “a” and “an” are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, “an element” means one element or more than one element.

By “about” is meant a quantity, level, value, number, frequency, percentage, dimension, size, amount, weight or length that varies by as much as 30, 25, 20, 25, 10, 9, 8, 7, 6, 5, 4, 3, 2 or 1% to a reference quantity, level, value, number, frequency, percentage, dimension, size, amount, weight or length.

By “coding sequence” is meant any nucleic acid sequence that contributes to the code for the polypeptide product of a gene. By contrast, the term “non-coding sequence” refers to any nucleic acid sequence that does not contribute to the code for the polypeptide product of a gene.

Throughout this specification, unless the context requires otherwise, the words “comprise,” “comprises,” and “comprising” will be understood to imply the inclusion of a stated step or element or group of steps or elements but not the exclusion of any other step or element or group of steps or elements.

By “consisting of” is meant including, and limited to, whatever follows the phrase “consisting of.” Thus, the phrase “consisting of” indicates that the listed elements are required or mandatory, and that no other elements may be present. By “consisting essentially of” is meant including any elements listed after the phrase, and limited to other elements that do not interfere with or contribute to the activity or action specified in the disclosure for the listed elements. Thus, the phrase “consisting essentially of” indicates that the listed elements are required or mandatory, but that other elements are optional and may or may not be present depending upon whether or not they materially affect the activity or action of the listed elements.

The terms “complementary” and “complementarity” refer to polynucleotides (i.e., a sequence of nucleotides) related by the base-pairing rules. For example, the sequence “A-G-T,” is complementary to the sequence “T-C-A.” Complementarity may be “partial,” in which only some of the nucleic acids' bases are matched according to the base pairing rules. Or, there may be “complete” or “total” complementarity between the nucleic acids. The degree of complementarity between nucleic acid strands has significant effects on the efficiency and strength of hybridization between nucleic acid strands. While perfect complementarity is often desired, some embodiments can include one or more but preferably 6, 5, 4, 3, 2, or 1 mismatches with respect to the target RNA. Variations at any location within the oligomer are included. In certain embodiments, variations in sequence near the termini of an oligomer are generally preferable to variations in the interior, and if present are typically within about 6, 5, 4, 3, 2, or 1 nucleotides of the 5′ and/or 3′ terminus.

The terms “cell penetrating peptide” or “CPP” are used interchangeably and refer to cationic cell penetrating peptides, also called transport peptides, carrier peptides, or peptide transduction domains. The peptides, as shown herein, have the capability of inducing cell penetration within 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% of cells of a given cell culture population, including all integers in between, and allow macromolecular translocation within multiple tissues in vivo upon systemic administration.

The terms “antisense oligomer” or “antisense compound” or “antisense oligonucleotide” or “oligonucleotide” are used interchangeably and refer to a sequence of cyclic subunits, each bearing a base-pairing moiety, linked by intersubunit linkages that allow the base-pairing moieties to hybridize to a target sequence in a nucleic acid (typically an RNA) by Watson-Crick base pairing, to form a nucleic acid:oligomer heteroduplex within the target sequence. The cyclic subunits may be based on ribose or another pentose sugar or, in certain embodiments, a morpholino group (see description of morpholino oligomers below). Also contemplated are peptide nucleic acids (PNAs), locked nucleic acids (LNAs), 2′-O-Methyl oligonucleotides and RNA interference agents (siRNA agents), and other antisense agents known in the art.

Such an antisense oligomer can be designed to block or inhibit translation of mRNA or to inhibit natural pre-mRNA splice processing, or induce degradation of targeted mRNAs, and may be said to be “directed to” or “targeted against” a target sequence with which it hybridizes. In certain embodiments, the target sequence includes a region including an AUG start codon of an mRNA, a 3′ or 5′ splice site of a pre-processed mRNA, a branch point. The target sequence may be within an exon or within an intron. The target sequence for a splice site may include an mRNA sequence having its 5′ end 1 to about 25 base pairs downstream of a normal splice acceptor junction in a preprocessed mRNA. A preferred splice site target sequence is any region of a preprocessed mRNA that includes a splice site or is contained entirely within an exon coding sequence or spans a splice acceptor or donor site. An oligomer is more generally said to be “targeted against” a biologically relevant target, such as a protein, virus, or bacteria, when it is targeted against the nucleic acid of the target in the manner described above.

Included are antisense oligonucleotides that comprise, consist essentially of, or consist of one or more of SEQ ID NOS:12-114. Also included are variants of these antisense oligomers, including variant oligomers having 80%, 85%, 90%, 95%, 97%, 98%, or 99% (including all integers in between) sequence identity or sequence homology to any one of SEQ ID NOS: 12-114, and/or variants that differ from these sequences by about 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleotides, preferably those variants that inhibit influenza replication in a cell. Also included are oligonucleotides of any one or more of SEQ ID NOS: 12-114, which comprise a suitable number of charged linkages, as described herein, e.g., up to about 1 per every 2-5 uncharged linkages, such as about 4-5 per every 10 uncharged linkages, and/or which comprise an Arg-rich peptide attached thereto, as also described herein.

The terms “morpholino oligomer” or “PMO” (phosphoramidate- or phosphorodiamidate morpholino oligomer) refer to an oligonucleotide analog composed of morpholino subunit structures, where (i) the structures are linked together by phosphorus-containing linkages, one to three atoms long, preferably two atoms long, and preferably uncharged or cationic, joining the morpholino nitrogen of one subunit to a 5′ exocyclic carbon of an adjacent subunit, and (ii) each morpholino ring bears a purine or pyrimidine or an equivalent base-pairing moiety effective to bind, by base specific hydrogen bonding, to a base in a polynucleotide. See, for example, the structure in FIG. 1A, which shows a preferred phosphorodiamidate linkage type. Variations can be made to this linkage as long as they do not interfere with binding or activity. For example, the oxygen attached to phosphorus may be substituted with sulfur (thiophosphorodiamidate). The 5′ oxygen may be substituted with amino or lower alkyl substituted amino. The pendant nitrogen attached to phosphorus may be unsubstituted, monosubstituted, or disubstituted with (optionally substituted) lower alkyl. See also the discussion of cationic linkages below. The purine or pyrimidine base pairing moiety is typically adenine, cytosine, guanine, uracil, thymine or inosine. The synthesis, structures, and binding characteristics of morpholino oligomers are detailed in U.S. Pat. Nos. 5,698,685, 5,217,866, 5,142,047, 5,034,506, 5,166,315, 5,521,063, and 5,506,337, and PCT Appn. Nos. PCT/US07/11435 (cationic linkages) and PCT Application No. US2008/012804 (improved synthesis), all of which are incorporated herein by reference.

The term “oligonucleotide analog” refers to an oligonucleotide having (i) a modified backbone structure, e.g., a backbone other than the standard phosphodiester linkage found in natural oligo- and polynucleotides, and (ii) optionally, modified sugar moieties, e.g., morpholino moieties rather than ribose or deoxyribose moieties. Oligonucleotide analogs support bases capable of hydrogen bonding by Watson-Crick base pairing to standard polynucleotide bases, where the analog backbone presents the bases in a manner to permit such hydrogen bonding in a sequence-specific fashion between the oligonucleotide analog molecule and bases in a standard polynucleotide (e.g., single-stranded RNA or single-stranded DNA). Preferred analogs are those having a substantially uncharged, phosphorus containing backbone.

A substantially uncharged, phosphorus containing backbone in an oligonucleotide analog is one in which a majority of the subunit linkages, e.g., between 50-100%, typically at least 60% to 100% or 75% or 80% of its linkages, are uncharged or substantially uncharged, and contain a single phosphorous atom. Antisense oligonucleotides and oligonucleotide analogs may contain between about 8 and 40 subunits, typically about 8-25 subunits, and preferably about 12 to 25 subunits. In certain embodiments, oligonucleotides may have exact sequence complementarity to the target sequence or near complementarity, as defined below.

A “subunit” of an oligonucleotide refers to one nucleotide (or nucleotide analog) unit. The term may refer to the nucleotide unit with or without the attached intersubunit linkage, although, when referring to a “charged subunit”, the charge typically resides within the intersubunit linkage (e.g., a phosphate or phosphorothioate linkage or a cationic linkage, as shown in FIG. 1B).

The purine or pyrimidine base pairing moiety is typically adenine, cytosine, guanine, uracil, thymine or inosine. Also included are bases such as pyridin-4-one, pyridin-2-one, phenyl, pseudouracil, 2,4,6-trime115thoxy benzene, 3-methyl uracil, dihydrouridine, naphthyl, aminophenyl, 5-alkylcytidines (e.g., 5-methylcytidine), 5-alkyluridines (e.g., ribothymidine), 5-halouridine (e.g., 5-bromouridine) or 6-azapyrimidines or 6-alkylpyrimidines (e.g. 6-methyluridine), propyne, quesosine, 2-thiouridine, 4-thiouridine, wybutosine, wybutoxosine, 4-acetyltidine, 5-(carboxyhydroxymethyl)uridine, 5″-carboxymethylaminomethyl-2-thiouridine, 5-carboxymethylaminomethyluridine, β-D-galactosylqueosine, 1-methyladenosine, 1-methylinosine, 2,2-dimethylguanosine, 3-methylcytidine, 2-methyladenosine, 2-methylguanosine, N6-methyladenosine, 7-methylguanosine, 5-methoxyaminomethyl-2-thiouridine, 5-methylaminomethyluridine, 5-methylcarbonylmethyluridine, 5-methyloxyuridine, 5-methyl-2-thiouridine, 2-methylthio-N6-isopentenyladenosine, β-D-mannosylqueosine, uridine-5-oxyacetic acid, 2-thiocytidine, threonine derivatives and others (Burgin et al., 1996, Biochemistry, 35, 14090; Uhlman & Peyman, supra). By “modified bases” in this aspect is meant nucleotide bases other than adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U), as illustrated above; such bases can be used at any position in the antisense molecule. Persons skilled in the art will appreciate that depending on the uses of the oligomers, Ts and Us are interchangeable. For instance, with other antisense chemistries such as 2′-O-methyl antisense oligonucleotides that are more RNA-like, the T bases may be shown as U (see, e.g., Sequence Listing).

An “amino acid subunit” or “amino acid residue” can refer to an α-amino acid residue (—CO—CHR—NH—) or a β- or other amino acid residue (e.g., —CO—(CH₂)_(n)—CHR—NH—), where R is a side chain (which may include hydrogen) and n is 1 to 7, preferably 1 to 4.

The term “naturally occurring amino acid” refers to an amino acid present in proteins found in nature, such as the 20 (L)-amino acids utilized during protein biosynthesis as well as others such as 4-hydroxyproline, hydroxylysine, desmosine, isodesmosine, homocysteine, citrulline and ornithine. The term “non-natural amino acids” refers to those amino acids not present in proteins found in nature, examples include beta-alanine (β-Ala), 6-aminohexanoic acid (Ahx) and 6-aminopentanoic acid. Additional examples of “non-natural amino acids” include, without limitation, (D)-amino acids, norleucine, norvaline, p-fluorophenylalanine, ethionine and the like, which are known to a person skilled in the art.

By “isolated” is meant material that is substantially or essentially free from components that normally accompany it in its native state. For example, an “isolated polynucleotide” or “isolated oligonucleotide,” as used herein, may refer to a polynucleotide that has been purified or removed from the sequences that flank it in a naturally-occurring state, e.g., a DNA fragment that has been removed from the sequences that are normally adjacent to the fragment.

An “effective amount” or “therapeutically effective amount” refers to an amount of therapeutic compound, such as an antisense oligomer or RNA interference agent (e.g., siRNA), administered to a mammalian subject, either as a single dose or as part of a series of doses, which is effective to produce a desired therapeutic effect. For an antisense oligomer, this effect is typically brought about by inhibiting translation or natural splice-processing of a selected target sequence. An “effective amount,” targeted against an infecting influenza virus, also relates to an amount effective to reduce the rate of replication of the infecting virus, and/or viral load, and/or symptoms associated with the viral infection.

By “enhance” or “enhancing,” or “increase” or “increasing,” or “stimulate” or “stimulating,” refers generally to the ability of one or antisense or RNAi compounds or compositions to produce or cause a greater physiological response (i.e., downstream effects) in a cell or a subject, as compared to the response caused by either no antisense compound or a control compound. An “increased” or “enhanced” amount is typically a “statistically significant” amount, and may include an increase that is 1.1, 1.2, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 30, 40, 50 or more times (e.g., 500, 1000 times) (including all integers and decimal points in between and above 1), e.g., 1.5, 1.6, 1.7. 1.8, etc.) the amount produced by no antisense compound (the absence of an agent) or a control compound.

The term “reduce” or “inhibit” may relate generally to the ability of one or more antisense or RNAi compounds of the invention to “decrease” a relevant physiological or cellular response, such as a symptom of a disease or condition described herein, as measured according to routine techniques in the diagnostic art. Relevant physiological or cellular responses (in vivo or in vitro) will be apparent to persons skilled in the art, and may include reductions in the symptoms or pathology of influenza infection, or reductions in viral replication or viral load. A “decrease” in a response may be “statistically significant” as compared to the response produced by no antisense compound or a control composition, and may include a 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% decrease, including all integers in between.

The term “target sequence” refers to a portion of the target RNA against which the oligonucleotide or antisense agent is directed, that is, the sequence to which the oligonucleotide will hybridize by Watson-Crick base pairing of a complementary sequence. In certain embodiments, the target sequence may be a contiguous region of the viral negative-strand RNA or viral mRNA, or may be composed of regions of the 5′ and 3′ terminal sequences of the viral genomic or viral complementary RNA.

The term “targeting sequence” or “antisense targeting sequence” refers to the sequence in an oligonucleotide or other antisense agent that is complementary (meaning, in addition, substantially complementary) to the target sequence in the RNA genome. The entire sequence, or only a portion, of the antisense compound may be complementary to the target sequence. For example, in an oligonucleotide having 20-30 bases, about 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, or 29 may be targeting sequences that are complementary to the target region. Typically, the targeting sequence is formed of contiguous bases, but may alternatively be formed of non-contiguous sequences that when placed together, e.g., from opposite ends of the oligonucleotide, constitute sequence that spans the target sequence.

The target and targeting sequences may be selected such that binding of the antisense compound is to a region within; 1) the 5′ or 3′ terminal 25 bases of the negative sense viral RNA; 2) the terminal 30 bases of the 5′ or 3′ terminus of the positive sense mRNA; 3) 45 bases surrounding the AUG start codons of viral mRNA and/or; 4) 50 bases surrounding the splice donor or acceptor sites of viral mRNAs subject to alternative splicing. In certain embodiments, the target region may include 1) the 5′ or 3′ terminal 25 bases of the M1 or M2 region of the negative sense viral RNA; 2) the terminal 30 bases of the 5′ or 3′ terminus of the positive sense M1 or M2 mRNA; 3) 45 bases surrounding the AUG start codons of the M1 or M2 mRNA and/or; 4) 50 bases surrounding the splice donor or acceptor sites of M1 or M2 viral mRNAs. In certain embodiments, the target region may comprise both the AUG codon and the bases surrounding or contributing to the splice donor site of the viral RNA (e.g., M1 or M2 mRNA), such as a polypyrimidine tract or lariat-forming sequence. In certain embodiments, using a single antisense oligomer or RNAi agent to target both the AUG start codon and the proximal splice donor sequences (e.g., polypyrimidine tract) of the M1/M2 RNA may provide synergistic effects with regard to reducing target protein expression, reducing viral replication, or both.

Target and targeting sequences are described as “complementary” to one another when hybridization occurs in an antiparallel configuration. A targeting sequence may have “near” or “substantial” complementarity to the target sequence and still function for the purpose of the present invention, that is, it may still be functionally “complementary.” In certain embodiments, an oligonucleotide may have at most one mismatch with the target sequence out of 10 nucleotides, and preferably at most one mismatch out of 20. Alternatively, an oligonucleotide may have at least 90% sequence homology, and preferably at least 95% sequence homology, with the exemplary antisense targeting sequences described herein.

An oligonucleotide “specifically hybridizes” to a target polynucleotide if the oligomer hybridizes to the target under physiological conditions, with a Tm substantially greater than 45° C., preferably at least 50° C., and typically 60° C.-80° C. or higher. Such hybridization preferably corresponds to stringent hybridization conditions. At a given ionic strength and pH, the Tm is the temperature at which 50% of a target sequence hybridizes to a complementary polynucleotide. Again, such hybridization may occur with “near” or “substantial” complementarity of the antisense oligomer to the target sequence, as well as with exact complementarity.

“Homology” refers to the percentage number of amino acids that are identical or constitute conservative substitutions. Homology may be determined using sequence comparison programs such as GAP (Deveraux et al., 1984, Nucleic Acids Research 12, 387-395). In this way sequences of a similar or substantially different length to those cited herein could be compared by insertion of gaps into the alignment, such gaps being determined, for example, by the comparison algorithm used by GAP.

The recitations “sequence identity” or, for example, comprising a “sequence 50% identical to,” as used herein, refer to the extent that sequences are identical on a nucleotide-by-nucleotide basis or an amino acid-by-amino acid basis over a window of comparison. Thus, a “percentage of sequence identity” may be calculated by comparing two optimally aligned sequences over the window of comparison, determining the number of positions at which the identical nucleic acid base (e.g., A, T, C, G, I) or the identical amino acid residue (e.g., Ala, Pro, Ser, Thr, Gly, Val, Leu, Ile, Phe, Tyr, Trp, Lys, Arg, H is, Asp, Glu, Asn, Gln, Cys and Met) occurs in both sequences to yield the number of matched positions, dividing the number of matched positions by the total number of positions in the window of comparison (i.e., the window size), and multiplying the result by 100 to yield the percentage of sequence identity.

Terms used to describe sequence relationships between two or more polynucleotides or polypeptides include “reference sequence,” “comparison window,” “sequence identity,” “percentage of sequence identity,” and “substantial identity”. A “reference sequence” is at least 8 or 10 but frequently 15 to 18 and often at least 25 monomer units, inclusive of nucleotides and amino acid residues, in length. Because two polynucleotides may each comprise (1) a sequence (i.e., only a portion of the complete polynucleotide sequence) that is similar between the two polynucleotides, and (2) a sequence that is divergent between the two polynucleotides, sequence comparisons between two (or more) polynucleotides are typically performed by comparing sequences of the two polynucleotides over a “comparison window” to identify and compare local regions of sequence similarity. A “comparison window” refers to a conceptual segment of at least 6 contiguous positions, usually about 50 to about 100, more usually about 100 to about 150 in which a sequence is compared to a reference sequence of the same number of contiguous positions after the two sequences are optimally aligned. The comparison window may comprise additions or deletions (i.e., gaps) of about 20% or less as compared to the reference sequence (which does not comprise additions or deletions) for optimal alignment of the two sequences. Optimal alignment of sequences for aligning a comparison window may be conducted by computerized implementations of algorithms (GAP, BESTFIT, FASTA, and TFASTA in the Wisconsin Genetics Software Package Release 7.0, Genetics Computer Group, 575 Science Drive Madison, Wis., USA) or by inspection and the best alignment (i.e., resulting in the highest percentage homology over the comparison window) generated by any of the various methods selected. Reference also may be made to the BLAST family of programs as for example disclosed by Altschul et al., 1997, Nucl. Acids Res. 25:3389. A detailed discussion of sequence analysis can be found in Unit 19.3 of Ausubel et al., “Current Protocols in Molecular Biology,” John Wiley & Sons Inc, 1994-1998, Chapter 15.

A “nuclease-resistant” oligomeric molecule (oligomer) refers to one whose backbone is substantially resistant to nuclease cleavage, in non-hybridized or hybridized form; by common extracellular and intracellular nucleases in the body; that is, the oligomer shows little or no nuclease cleavage under normal nuclease conditions in the body to which the oligomer is exposed.

A “heteroduplex” refers to a duplex between an antisense oligonucleotide and the complementary portion of a target RNA. A “nuclease-resistant heteroduplex” refers to a heteroduplex formed by the binding of an antisense oligomer to its complementary target, such that the heteroduplex is substantially resistant to in vivo degradation by intracellular and extracellular nucleases, such as RNaseH, which are capable of cutting double-stranded RNA/RNA or RNA/DNA complexes.

A “base-specific intracellular binding event involving a target RNA” refers to the specific binding of an antisense oligonucleotide to a target RNA sequence inside a cell. The base specificity of such binding is sequence dependent. For example, a single-stranded polynucleotide can specifically bind to a single-stranded polynucleotide that is complementary in sequence.

As used herein, the term “body fluid” encompasses a variety of sample types obtained from a subject including, urine, saliva, plasma, blood, spinal fluid, or other sample of biological origin, such as skin cells or dermal debris, and may refer to cells or cell fragments suspended therein, or the liquid medium and its solutes.

The term “relative amount” is used where a comparison is made between a test measurement and a control measurement. The relative amount of a reagent forming a complex in a reaction is the amount reacting with a test specimen, compared with the amount reacting with a control specimen. The control specimen may be run separately in the same assay, or it may be part of the same sample (for example, normal tissue surrounding a malignant area in a tissue section).

“Treatment” of an individual or a cell is any type of intervention provided as a means to alter the natural course of a disease or pathology in the individual or cell. Treatment includes, but is not limited to, administration of, e.g., a pharmaceutical composition, and may be performed either prophylactically, or subsequent to the initiation of a pathologic event or contact with an etiologic agent. Treatment includes any desirable effect on the symptoms or pathology of a disease or condition associated with influenza virus infection. The related term “improved therapeutic outcome” relative to a patient diagnosed as infected with a particular virus, may refer to a slowing or diminution in the growth of virus, or viral load, or detectable symptoms associated with infection by that particular virus.

Also included are “prophylactic” treatments, which can be directed to reducing the rate of progression of the disease or condition being treated, delaying the onset of that disease or condition, or reducing the severity of its onset. “Treatment” or “prophylaxis” does not necessarily indicate complete eradication, cure, or prevention of the disease or condition, or associated symptoms thereof.

An agent is “actively taken up by mammalian cells” when the agent can enter the cell by a mechanism other than passive diffusion across the cell membrane. The agent may be transported, for example, by “active transport,” referring to transport of agents across a mammalian cell membrane by e.g., an ATP-dependent transport mechanism, or by “facilitated transport,” referring to transport of antisense agents across the cell membrane by a transport mechanism that requires binding of the agent to a transport protein, which then facilitates passage of the bound agent across the membrane. For both active and facilitated transport, oligonucleotide analogs preferably have a substantially uncharged backbone, as defined below.

Alternatively, the antisense compound may be formulated in a complexed form, such as an agent having an anionic backbone complexed with cationic lipids or liposomes, which can be taken into cells by an endocytic mechanism. The antisense oligonucleotide may also be conjugated, e.g., at its 5′ or 3′ end, to an arginine-rich peptide, such as a portion of the HIV TAT protein, polyarginine, or to combinations of arginine and other amino acids including the non-natural amino acids 6-aminohexanoic acid (Ahx) and beta-alanine (βAla). Exemplary arginine-rich delivery peptides are listed as SEQ ID NOs:115-128. These exemplary arginine-rich delivery peptides facilitate transport into the target host cell as described (Moulton, Nelson et al. 2004).

Hence, included are methods of treating an influenza virus infection, by administering one or more antisense oligomers of the present invention (e.g., SEQ ID NOS:12-114, and variants thereof), optionally as part of a pharmaceutical formulation or dosage form, to a subject in need thereof. A “subject,” as used herein, may include any animal that exhibits a symptom, or is at risk for exhibiting a symptom, which can be treated with an antisense compound of the invention, such as a subject that has or is at risk for having an influenza virus infection. Suitable subjects (patients) include laboratory animals (such as mouse, rat, rabbit, or guinea pig), farm animals, and domestic animals or pets (such as a cat or dog). Non-human primates and, preferably, human patients, are included.

Also contemplated are alternate methods of RNA interference (RNAi), such as those involving double stranded RNA-molecules, or dsRNA. The term “double-stranded” means two separate nucleic acid strands comprising a region in which at least a portion of the strands are sufficiently complementary to hydrogen bond and form a duplex structure. The term “duplex” or “duplex structure” refers to the region of a double stranded molecule wherein the two separate strands are substantially complementary, and thus hybridize to each other.

“dsRNA” refers to a ribonucleic acid molecule having a duplex structure comprising two complementary and anti-parallel nucleic acid strands (i.e., the sense and antisense strands). Not all nucleotides of a dsRNA must exhibit Watson-Crick base pairs; the two RNA strands may be substantially complementary. The RNA strands may have the same or a different number of nucleotides. The term “dsRNA” also includes “siRNA” or short interfering RNA.

It will be understood that the term “ribonucleotide” or “nucleotide” can, in the case of a modified RNA or nucleotide surrogate, also refer to a modified nucleotide, or surrogate replacement moiety at one or more positions. Thus, the dsRNA is or includes a region which is at least partially complementary to the target RNA. In certain embodiments, the dsRNA is fully complementary to the target RNA. It is not necessary that there be perfect complementarity between the dsRNA and the target, but the correspondence must be sufficient to enable the dsRNA, or a cleavage product thereof, to direct sequence specific silencing, such as by RNAi cleavage of the target RNA. Complementarity, or degree of homology with the target strand, is most critical in the antisense strand. While perfect complementarity, particularly in the antisense strand, is often desired some embodiments can include one or more but preferably 6, 5, 4, 3, 2, or fewer mismatches with respect to the target RNA. The mismatches are most tolerated in the terminal regions, and if present are preferably in a terminal region or regions, e.g., within 6, 5, 4, or 3 nucleotides of the 5′ and/or 3′ terminus. The sense strand need only be substantially complementary with the antisense strand to maintain the overall double-strand character of the molecule.

As used herein, “modified dsRNA” refers to a dsRNA molecule that comprises at least one alteration that renders it more resistant to nucleases (e.g., protein kinase) than an identical dsRNA molecule that recognizes the same target RNA. Modified dsRNAs may include a single-stranded nucleotide overhang and/or at least one substituted nucleotide.

As used herein, a “nucleotide overhang” refers to the unpaired nucleotide or nucleotides that protrude from the duplex structure when a 3′-end of one RNA strand extends beyond the 5′-end of the other complementary strand, or vice versa. “Blunt” or “blunt end” means that there are no unpaired nucleotides at that end of the dsRNA, i.e., no nucleotide overhang. A “blunt ended” dsRNA is a dsRNA that is double stranded over its entire length, i.e., no nucleotide overhang at either end of the molecule.

The term “terminal base pair,” as used herein, refers to the last nucleotide base pair on one end of the duplex region of a double-stranded molecule. For example, if a dsRNA or other molecule is blunt ended (i.e., has no nucleotide overhangs), the last nucleotide base pairs at both ends of the molecule are terminal base pairs. Where a dsRNA or other molecule has a nucleotide overhang at one or both ends of the duplex structure, the last nucleotide base pair(s) immediately adjacent the nucleotide overhang(s) is the terminal base pair at that end(s) of the molecule.

Also included are vector delivery systems that are capable of expressing the oligomeric, influenza virus-targeting sequences of the present invention, such as vectors that express a polynucleotide sequence comprising any one or more of SEQ ID NOS:12-114, or variants thereof, as described herein, or that express a polynucleotide sequence that is complementary to any or more of the target sequences of SEQ ID NOS:1-11. Included are vectors that express siRNA or other duplex-forming RNA interference molecules.

By “vector” or “nucleic acid construct” is meant a polynucleotide molecule, preferably a DNA molecule derived, for example, from a plasmid, bacteriophage, yeast or virus, into which a polynucleotide can be inserted or cloned. A vector preferably contains one or more unique restriction sites and can be capable of autonomous replication in a defined host cell including a target cell or tissue or a progenitor cell or tissue thereof, or be integrable with the genome of the defined host such that the cloned sequence is reproducible. Accordingly, the vector can be an autonomously replicating vector, i.e., a vector that exists as an extra-chromosomal entity, the replication of which is independent of chromosomal replication, e.g., a linear or closed circular plasmid, an extra-chromosomal element, a mini-chromosome, or an artificial chromosome. The vector can contain any means for assuring self-replication. Alternatively, the vector can be one which, when introduced into the host cell, is integrated into the genome and replicated together with the chromosome(s) into which it has been integrated.

A vector or nucleic acid construct system can comprise a single vector or plasmid, two or more vectors or plasmids, which together contain the total DNA to be introduced into the genome of the host cell, or a transposon. The choice of the vector will typically depend on the compatibility of the vector with the host cell into which the vector is to be introduced. In the present case, the vector or nucleic acid construct is preferably one which is operably functional in a mammalian cell, such as a muscle cell. The vector can also include a selection marker such as an antibiotic or drug resistance gene, or a reporter gene (i.e., green fluorescent protein, luciferase), that can be used for selection or identification of suitable transformants or transfectants. Exemplary delivery systems may include viral vector systems (i.e., viral-mediated transduction) including, but not limited to, retroviral (e.g., lentiviral) vectors, adenoviral vectors, adeno-associated viral vectors, and herpes viral vectors, among others known in the art.

The term “operably linked” as used herein means placing an oligomer-encoding sequence under the regulatory control of a promoter, which then controls the transcription of the oligomer.

A wild-type gene or gene product is that which is most frequently observed in a population and is thus arbitrarily designed the “normal” or “wild-type” form of the gene.

“Alkyl” refers to a fully saturated monovalent radical containing carbon and hydrogen, which may be branched, linear, or cyclic (cycloalkyl). Examples of alkyl groups are methyl, ethyl, n-butyl, t-butyl, n-heptyl, isopropyl, cyclopropyl, cyclopentyl, ethylcyclopentyl, and cyclohexyl. Generally preferred are alkyl groups having one to six carbon atoms, referred to as “lower alkyl”, and exemplified by methyl, ethyl, n-butyl, i-butyl, t-butyl, isoamyl, n-pentyl, and isopentyl. In one embodiment, lower alkyl refers to C₁ to C₄ alkyl.

“Alkenyl” refers to an unsaturated monovalent radical containing carbon and hydrogen, which may be branched, linear, or cyclic. The alkenyl group may be monounsaturated or polyunsaturated. Generally preferred are alkenyl groups having one to six carbon atoms, referred to as “lower alkenyl.”

“Alkynyl” refers to an unsaturated straight or branched chain hydrocarbon radical containing from 2 to 18 carbons comprising at least one carbon to carbon triple bond. Examples include without limitation ethynyl, propynyl, iso-propynyl, butynyl, iso-butynyl, tert-butynyl, pentynyl and hexynyl. The term “lower alkynyl” refers to an alkynyl group, as defined herein, containing between 2 and 8 carbons.

“Cycloalkyl” refers to a mono- or poly-cyclic alkyl radical. Examples include without limitation cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl.

“Aryl” refers to a substituted or unsubstituted monovalent aromatic radical, generally having a single ring (e.g., phenyl) or two condensed rings (e.g., naphthyl). This term includes heteroaryl groups, which are aromatic ring groups having one or more nitrogen, oxygen, or sulfur atoms in the ring, such as furyl, pyrrolyl, pyridyl, and indolyl. By “substituted” is meant that one or more ring hydrogens in the aryl group is replaced with a halide such as fluorine, chlorine, or bromine; with a lower alkyl group containing one or two carbon atoms; nitro, amino, methylamino, dimethylamino, methoxy, halomethoxy, halomethyl, or haloethyl. Preferred substituents include halogen, methyl, ethyl, and methoxy. Generally preferred are aryl groups having a single ring.

“Aralkyl” refers to an alkyl, preferably lower (C₁-C₄, more preferably C₁-C₂) alkyl, substituent which is further substituted with an aryl group; examples are benzyl (—CH₂C₆H₅) and phenethyl (—CH₂CH₂C₆H₅).

“Thioalkoxy” refers to a radical of the formula —SRc where Rc is an alkyl radical as defined herein. The term “lower thioalkoxy” refers to an alkoxy group, as defined herein, containing between 1 and 8 carbons.

“Alkoxy” refers to a radical of the formula —ORda where Rd is an alkyl radical as defined herein. The term “lower alkoxy” refers to an alkoxy group, as defined herein, containing between 1 and 8 carbons. Examples of alkoxy groups include, without limitation, methoxy and ethoxy.

“Alkoxyalkyl” refers to an alkyl group substituted with an alkoxy group.

“Carbonyl” refers to the —C(═O)— radical.

“Guanidynyl” refers to the H₂N(C═NH₂)—NH— radical.

“Amidinyl” refers to the H₂N(C═NH₂)CH— radical.

“Amino” refers to the —NH₂ radical.

“Alkylamino” refers to a radical of the formula —NHRd or —NRdRd where each Rd is, independently, an alkyl radical as defined herein. The term “lower alkylamino” refers to an alkylamino group, as defined herein, containing between 1 and 8 carbons.

“Heterocycle” means a 5- to 7-membered monocyclic, or 7- to 10-membered bicyclic, heterocyclic ring which is either saturated, unsaturated, or aromatic, and which contains from 1 to 4 heteroatoms independently selected from nitrogen, oxygen and sulfur, and wherein the nitrogen and sulfur heteroatoms may be optionally oxidized, and the nitrogen heteroatom may be optionally quaternized, including bicyclic rings in which any of the above heterocycles are fused to a benzene ring. The heterocycle may be attached via any heteroatom or carbon atom. Preferably, the ring atoms include 3 to 6 carbon atoms. Such heterocycles include, for example, pyrrolidine, piperidine, piperazine, and morpholine.

Heterocycles include heteroaryls as defined below. Thus, in addition to the heteroaryls listed below, heterocycles also include morpholinyl, pyrrolidinonyl, pyrrolidinyl, piperidinyl, piperizynyl, hydantoinyl, valerolactamyl, oxiranyl, oxetanyl, tetrahydrofuranyl, tetrahydropyranyl, tetrahydropyridinyl, tetrahydrothiophenyl, tetrahydrothiopyranyl, tetrahydropyrimidinyl, tetrahydrothiopyranyl, and the like.

“Heteroaryl” means an aromatic heterocycle ring of 5- to 10 members and having at least one heteroatom selected from nitrogen, oxygen and sulfur, and containing at least 1 carbon atom, including both mono- and bicyclic ring systems. Representative heteroaryls are pyridyl, furyl, benzofuranyl, thiophenyl, benzothiophenyl, quinolinyl, pyrrolyl, indolyl, oxazolyl, benzoxazolyl, imidazolyl, benzimidazolyl, thiazolyl, benzothiazolyl, isoxazolyl, pyrazolyl, isothiazolyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, cinnolinyl, phthalazinyl, and quinazolinyl.

The term “substituted”, with respect to an alkyl, alkenyl, alkynyl, aryl, aralkyl, or alkaryl group, refers to replacement of a hydrogen atom with a heteroatom-containing substituent, such as, for example, halogen, hydroxy, alkoxy, thiol, alkylthio, amino, alkylamino, imino, oxo(keto), nitro, cyano, or various acids or esters such as carboxylic, sulfonic, or phosphonic.

The term “substituted”, particularly with respect to an alkyl, alkoxy, thioalkoxy, or alkylamino group, refers to replacement of a hydrogen atom on carbon with a heteroatom-containing substituent, such as, for example, halogen, hydroxy, alkoxy, thiol, alkylthio, amino, alkylamino, imino, oxo(keto), nitro, cyano, or various acids or esters such as carboxylic, sulfonic, or phosphonic. It may also refer to replacement of a hydrogen atom on a heteroatom (such as an amine hydrogen) with an alkyl, carbonyl or other carbon containing group.

In certain embodiments, the terms “optionally substituted alkyl”, “optionally substituted alkenyl”, “optionally substituted alkoxy”, “optionally substituted thioalkoxy”, “optionally substituted alkyl amino”, “optionally substituted lower alkyl”, “optionally substituted lower alkenyl”, “optionally substituted lower alkoxy”, “optionally substituted lower thioalkoxy”, “optionally substituted lower alkyl amino” and “optionally substituted heterocyclyl” mean that, when substituted, at least one hydrogen atom is replaced with a substituent. In the case of an oxo substituent (═O) two hydrogen atoms are replaced. In this regard, substituents include: deuterium, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heterocycle, optionally substituted cycloalkyl, oxo, halogen, —CN, —ORx, NRxRy, NRxC(═O)Ry, NRxSO2Ry, —NRxC(═O)NRxRy, C(═O)Rx, C(═O)ORx, C(═O)NRxRy, —SOmRx and —SOmNRxRy, wherein m is 0, 1 or 2, Rx and Ry are the same or different and independently hydrogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heterocycle or optionally substituted cycloalkyl and each of said optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heterocycle and optionally substituted cycloalkyl substituents may be further substituted with one or more of oxo, halogen, —CN, —ORx, NRxRy, NRxC(═O)Ry, NRxSO2Ry, —NRxC(═O)NRxRy, C(═O)Rx, C(═O)ORx, C(═O)NRxRy, —SOmRx and —SOmNRxRy.

The selection of targeting sequences capable of inhibiting replication of the influenza viral genome are discussed below.

Targeted Viruses

Embodiments of the present invention are based, in part, on the discovery that effective inhibition of single-stranded, segmented, negative-sense RNA viruses can be achieved by exposing animals infected with influenza virus to antisense oligonucleotide compounds (I) that target 1) the 5′ or 3′ terminal 25 bases of the negative sense viral RNA; 2) the terminal 30 bases of the 5′ or 3′ terminus of the positive sense mRNA; 3) 45 bases surrounding the AUG start codons of viral mRNA and/or; 4) 50 bases surrounding the splice donor or acceptor sites of influenza mRNAs subject to alternative splicing and (ii) having physical and pharmacokinetic features which allow effective interaction between the antisense compound and the virus within host cells. In certain embodiments, the oligomers can be used in treating a mammalian subject infected with influenza virus.

Certain embodiments target RNA viruses having genomes that are: (i) single stranded, (ii) segmented and (iii) negative polarity. The targeted viruses also synthesize two different versions of a genomic complement of the negative sense virion RNA (vRNA) with positive polarity: 1) cRNA that is used as a template for replication of negative sense virion RNA, and 2) a complementary positive sense RNA (mRNA) that is used for translation of viral proteins. FIG. 3 is an exemplary schematic that shows these different RNA species and the target location of antisense PMO described in the present invention.

Targeted viral families include members of the Orthomyxoviridae family including the Influenzavirus A, Influenzavirus B and Influenzavirus C genera. Various physical, morphological, and biological characteristics of members of the Orthomyxoviridae family can be found, for example, in Textbook of Human Virology, R. Belshe, ed., 2nd Edition, Mosby, 1991, at the Universal Virus Database of the International Committee on Taxonomy of Viruses (www.ncbi.nlm.nih.gov/ICTVdb/index.htm) and in human virology textbooks (see, for example (Strauss and Strauss 2002)). Some of the key biological characteristics of the Orthomxyoviridae family of viruses are described below.

Influenza A, influenza B and influenza C viruses are the only members of the Influenzavirus A, Influenzavirus B and Influenzavirus C genera, respectively. These viruses are membrane-enclosed viruses whose genomes are segmented negative-sense (i.e. minus) strands of RNA ((−)RNA). The ten influenza virus genes are present on eight segments of the single-stranded RNA of strains A and B, and on seven segments of strain C. The segments vary in size (from 890 to 2341 nucleotides in length) and each is a template for synthesis of different mRNAs. The influenza virus virion contains virus-specific RNA polymerases necessary for mRNA synthesis from these templates and, in the absence of such specific polymerases, the minus strand of influenza virus RNA is not infectious. Initiation of transcription of the mRNAs occurs when the influenza virus mRNA polymerase takes 12 to 15 nucleotides from the 5′ end of a cellular mRNA or mRNA precursor and uses the borrowed oligonucleotide as a primer. This process has been termed “cap-snatching” because it places a 5′ cap structure on the viral mRNA. Generally, the mRNAs made through this process encode only one protein. The M gene and NS gene viral RNA segments also code for spliced mRNAs, which results in production of two different proteins for each of these two segments.

Replication of influenza viral RNA occurs in the nucleus and involves the synthesis of three different species of RNA. A schematic of this process is shown in FIG. 3. After infection of a naïve cell, the minus strand virion RNA (vRNA) is transported to the nucleus where RNA destined for translation (mRNA) is synthesized using 5′-terminal 10-13 nucleotide primers cleaved by viral-encoded enzymes from capped cellular pre-mRNA molecules (i.e. cap-snatching). Synthesis of each mRNA continues to near the end of the genome segment where an oligo(U) stretch is encountered and a poly(A) tail is added. The dedicated viral mRNAs are transported to the cytoplasm for translation and after sufficient viral proteins are transported back into the nucleus, synthesis of vRNA destined for nascent virions is initiated. An exact antigenomic copy of vRNA is synthesized (termed cRNA) which is a perfect complement of the genomic vRNA and serves as a template for production of new vRNA. The different RNAs synthesized during influenza virus replication are shown schematically in FIG. 3.

GenBank references for exemplary viral nucleic acid target sequences representing influenza A genomic segments are listed in Table 1 below. The nucleotide sequence numbers in Table 1 are derived from the Genbank reference for the positive-strand RNA. It will be appreciated that these sequences are only illustrative of other sequences in the Orthomyxoviridae family, as may be available from available gene-sequence databases of literature or patent resources. The sequences below, identified as SEQ ID NOs:1-11, are also listed in the Sequence Listing at the end of the specification.

Table 1 lists the targets for the influenza A viral genes, M1 and M2 encoded by genomic segment 7. The target sequences in Table 1 represent; 1) the 3′ terminal 25 bases of the negative sense viral RNA (SEQ ID NO:4); 2) the terminal 25 bases of the 5′ terminus of the positive sense mRNA (SEQ ID NO:3); 3) 45 bases surrounding the AUG start codon of the indicated influenza virus genes (SEQ ID NO:2). The sequences shown are the positive-strand (i.e., antigenomic or mRNA) sequence in the 5′ to 3′ orientation except for SEQ ID NO: 4 which is the sequence of the minus-strand (i.e., genomic or virion RNA). It will be apparent that when the target is the minus-strand vRNA the targeted sequence is the complement of the sequence listed in Table 1 unless otherwise noted, e.g., SEQ ID NO:4.

The M1 and M2 proteins are components of the viral matrix protein and ion channel activity, respectively. The two proteins are produced from alternative splice forms of the segment 7 vcRNA that utilize the same AUG start site. The M2 protein is the target of two current anti-influenza therapeutics, amantadine and rimantadine. An exemplary target sequence for the AUG start codon region (−20 to +25 relative to the AUG start codon) of the M1/M2 genes is represented as SEQ ID NO: 2 which is a subsequence of the terminal 60 nucleotide region listed as SEQ ID NO:1. The 3′ terminal target sequence (25 nucleotides) of the M1/M2 segment is represented by SEQ ID NO:3 which is also a subsequence of the terminal 60 nucleotide region and can be targeted on both the positive strand (vcRNA) and the negative strand (vRNA) of the segment. The 5′ terminal sequence (SEQ ID NO:3) can be successfully targeted on the minus strand shown below as SEQ ID NO:4. SEQ ID NOs: 1-4 are from the 2009H1N1 virus (ω-OIV) and derived from an exemplary isolate of the virus found in the GenBank database under accession number GQ332646. 5′ terminal 60 nucleotide regions of other reference influenza A subtypes are listed in Table 1 as SEQ ID NOs: 5, 6, 7, 8 for H1N1, H5N1, H3N2 and H2N2, respectively. Corresponding AUG and terminal target regions can be derived from these viral sequences using the guidance described above.

It is also possible to target the splice donor and acceptor regions of the M1/M2 segment. The splice donor and splice acceptor sites are at nucleotides 51 and 740, respectively. Targeting of either splice junction using antisense compounds of the invention is contemplated. Furthermore, it is possible to block both the AUG start site and the splice donor site using an appropriately designed antisense compounds (e.g., SEQ ID NOs:12-16 and 19-22). The splice acceptor target region is shown below for the 2009H1N1 (S-OIV) subtype as SEQ ID NO: 10. The corresponding region for the H5N1 subtype is listed in Table 1 as SEQ ID NO: 9.

Furthermore, it is contemplated that any translation-sensitive, splice-sensitive or replication-sensitive region of the M1/M2 segment can be targeted using compounds of the invention. The reference M1/M2 (segment 7) sequence for the prototypic H1N1 subtype (Puerto Rico/8/34) is shown in Table 1 as SEQ ID NO:11 and can be found in the GenBank Reference Sequence database under NC_(—)002016. Corresponding M1/M2 segment sequences can be obtained from publicly available sequence databases. It is contemplated that antisense compounds of the invention can be targeted to other regions of this segment with the expectation that additional translation-, splice- and/or replication-sensitive target regions can be identified.

TABLE 1 Exemplary Influenza Viral Nucleic Acid Target Sequences NCBI Nct SEQ ID Name No. Region Sequence (5′ to 3′) NO M1/M2-trgt GQ332646 1-60 AGCAAAAGCAGGUAGAUAUUUAAAGAUGAGU 1 2009H1N1 CUUCUAACCGAGGUCGAAAC/GUACGUUCU M1/M2-AUG GQ332646 6-50 AAGCAGGUAGAUAUUUAAAGAUGAGUCUUC 2 UAACCGAGGUCGAAA M1/M2- GQ332646 1-25 AGCAAAAGCAGGUAGAUAUUUAAAG 3 vc5′trm M1/M2- GQ332646 1072-1097  CUUUAAAUAUCUACCUGCUUUUGCU 4 v3′trm M1/M2-trgt NC_002016 1-60 AGCGAAAGCAGGUAGAUAUUGAAAGAUGAGU 5 H1N1con CUUCUAACCGAGGUCGAAAC/GUACGUUCU M1/M2-trgt NC_007363 1-60 AGCAAAAGCAGGUAGAUAUUGAAAGAUGAGU 6 H5N1con CUUCUAACCGAGGUCGAAAC/GUACGUUCU M1/M2-trgt NC_007367 1-60 AGCAAAAGCAGGUAGAUAUUGAAAGAUGAGC 7 H3N2con CUUCUAACCGAGGUCGAAAC/GUAUGUUCU M1/M2-trgt NC_007377 1-60 AGCAAAAGCAGGUAGAUAUUGAAAGAUGAGU 8 H2N2con CUUCUAACCGAGGUCGAAAC/GUACGUUCU M1/M2-SA NC_007363 730-780  AAAUUUGCAG/GCCUACCAGAAACGAAUGGG 9 H5N1 AGUGCAGAUGCAGCGAUUCAA M1/M2-SA GQ332646 730-780  AAAUUUGCAG/GCCUACCAGAAGCGAAUGGG 10 2009H1N1 AGUGCAGAUGCAGCGAUUCAA M1/M2 NC_002016   1-1027 AGCGAAAGCAGGTAGATATTGAAAGATGAGT 11 H1N1 CTTCTAACCGAGGTCGAAACGTACGTTCTCT segment 7 CTATCATCCCGTCAGGCCCCCTCAAAGCCGA GATCGCACAGAGACTTGAAGATGTCTTTGCA GGGAAGAACACCGATCTTGAGGTTCTCATGG AATGGCTAAAGACAAGACCAATCCTGTCACC TCTGACTAAGGGGATTTTAGGATTTGTGTTC ACGCTCACCGTGCCCAGTGAGCGAGGACTGC AGCGTAGACGCTTTGTCCAAAATGCCCTTAA TGGGAACGGGGATCCAAATAACATGGACAAA GCAGTTAAACTGTATAGGAAGCTCAAGAGGG AGATAACATTCCATGGGGCCAAAGAAATCTC ACTCAGTTATTCTGCTGGTGCACTTGCCAGT TGTATGGGCCTCATATACAACAGGATGGGGG CTGTGACCACTGAAGTGGCATTTGGCCTGGT ATGTGCAACCTGTGAACAGATTGCTGACTCC CAGCATCGGTCTCATAGGCAAATGGTGACAA CAACCAACCCACTAATCAGACATGAGAACAG AATGGTTTTAGCCAGCACTACAGCTAAGGCT ATGGAGCAAATGGCTGGATCGAGTGAGCAAG CAGCAGAGGCCATGGAGGTTGCTAGTCAGGC TAGGCAAATGGTGCAAGCGATGAGAACCATT GGGACTCATCCTAGCTCCAGTGCTGGTCTGA AAAATGATCTTCTTGAAAATTTGCAGGCCTA TCAGAAACGAATGGGGGTGCAGATGCAACGG TTCAAGTGATCCTCTCGCTATTGCCGCAAAT ATCATTGGGATCTTGCACTTGATATTGTGGA TTCTTGATCGTCTTTTTTTCAAATGCATTTA CCGTCGCTTTAAATACGGACTGAAAGGAGGG CCTTCTACGGAAGGAGTGCCAAAGTCTATGA GGGAAGAATATCGAAAGGAACAGCAGAGTGC TGTGGATGCTGACGATGGTCATTTTGTCAGC ATAGAGCTGGAGTAAAAAACTACCTTGTTTC TACT

FIG. 4A shows the conservation of the 5′ terminal 60 nucleotides of the M1/M2 segment from important subtypes of influenza A: H1N1, H1N1(S-OIV), H5N1, H3N2, H9N2 and H7N7. FIG. 4B shows conservation of target sequences in one important serotype of influenza, H1N1 (2009), also known as swine-origin influenza A (S-OIV), for each base of a preferred PMO (M1/M2-AUG; SEQ ID NO: 12) based on the NCBI influenza database of genome sequences (Bao Y., P. Bolotov, D. Dernovoy, B. Kiryutin, L. Zaslaysky, T. Tatusova, J. Ostell, and D. Lipman. The Influenza Virus Resource at the National Center for Biotechnology Information. J. Virol. 2008 January; 82(2):596-601). The capital letter indicates the target base and the subscript number next to the base indicates the percent conservation for that base for the H1N1 (2009) isolates in the database as indicated above the sequence. These data indicate no base position shows any significant variation for the M1/M2-AUG target for H1N1 (2009).

In certain embodiments, antisense targeting sequences are designed to hybridize to a region of one or more of the target sequences listed in Table 1. Selected antisense targeting sequences can be made shorter, e.g., about 12 bases, or longer, e.g., about 40 bases, and include a small number of mismatches, as long as the sequence is sufficiently complementary to effect translational, splice and/or replication inhibition upon hybridization with the target, and forms with the viral RNA, a heteroduplex having a Tm of 45° C. or greater.

In certain embodiments, the degree of complementarity between the target and antisense targeting sequence is sufficient to form a stable duplex. The region of complementarity of the antisense oligomers with the target RNA sequence may be as short as 8-11 bases, but is preferably 12-15 bases or more, e.g., 12-20 bases, or 12-25 bases, including all integers in between these ranges. An antisense oligomer of about 14-15 bases is generally long enough to have a unique complementary sequence in the viral genome. In certain embodiments, a minimum length of complementary bases may be required to achieve the requisite binding Tm, as discussed below.

In certain embodiments, oligomers as long as 40 bases may be suitable, where at least a minimum number of bases, e.g., 10-12 bases, are complementary to the target sequence. In general, however, facilitated or active uptake in cells is optimized at oligomer lengths less than about 30. For PMO oligomers, described further below, an optimum balance of binding stability and uptake generally occurs at lengths of 18-25 bases. Included are antisense oligomers (e.g., PNAs, LNAs, 2′-OMe) and PMO oligomers that consist of about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40 bases, in which at least about 6, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or 40 contiguous or non-contiguous bases are complementary to the target sequences of SEQ ID NOS:1-11, or variants thereof.

In certain embodiments, antisense oligomers may be 100% complementary to the viral nucleic acid target sequence, or it may include mismatches, e.g., to accommodate variants, as long as a heteroduplex formed between the oligomer and viral nucleic acid target sequence is sufficiently stable to withstand the action of cellular nucleases and other modes of degradation which may occur in vivo. Oligomer backbones which are less susceptible to cleavage by nucleases are discussed below. Mismatches, if present, are less destabilizing toward the end regions of the hybrid duplex than in the middle. The number of mismatches allowed will depend on the length of the oligomer, the percentage of G:C base pairs in the duplex, and the position of the mismatch(es) in the duplex, according to well understood principles of duplex stability. Although such an antisense oligomer is not necessarily 100% complementary to the viral nucleic acid target sequence, it is effective to stably and specifically bind to the target sequence, such that a biological activity of the nucleic acid target, e.g., expression of viral protein(s), is modulated.

The stability of the duplex formed between an oligomer and a target sequence is a function of the binding Tm and the susceptibility of the duplex to cellular enzymatic cleavage. The Tm of an antisense compound with respect to complementary-sequence RNA may be measured by conventional methods, such as those described by Hames et al., Nucleic Acid Hybridization, IRL Press, 1985, pp. 107-108 or as described in Miyada C. G. and Wallace R. B., 1987, Oligonucleotide Hybridization Techniques, Methods Enzymol. Vol. 154 pp. 94-107. In certain embodiments, antisense oligomer may have a binding Tm, with respect to a complementary-sequence RNA, of greater than body temperature and preferably greater than about 45° C. or 50° C. Tm's in the range 60-80° C. or greater are preferred. According to well known principles, the Tm of an oligomer compound, with respect to a complementary-based RNA hybrid, can be increased by increasing the ratio of C:G paired bases in the duplex, and/or by increasing the length (in base pairs) of the heteroduplex. At the same time, for purposes of optimizing cellular uptake, it may be advantageous to limit the size of the oligomer. For this reason, compounds that show high Tm (45-50° C. or greater) at a length of 25 bases or less are generally preferred over those requiring greater than 25 bases for high Tm values.

In certain embodiments, such as PMO oligomers, the antisense activity of an oligomer may be enhanced by using a mixture of uncharged and cationic phosphorodiamidate linkages, as exemplified in FIG. 1B. The total number of cationic linkages in the oligomer can vary from 1 to 10 (including all integers in between), and be interspersed throughout the oligomer. Preferably the number of charged linkages is at least 2 and no more than half the total backbone linkages, e.g., between 2, 3, 4, 5, 6, 7, or 8 positively charged linkages, and preferably each charged linkages is separated along the backbone by at least 1, 2, 3, 4, or 5 uncharged linkages. The antisense activity of various oligomers can be measured in vitro by fusing the oligomer target region to the 5′ end a reporter gene (e.g., firefly luciferase) and then measuring the inhibition of translation of the fusion gene mRNA transcripts in cell free translation assays. The inhibitory properties of oligomers containing a mixture of uncharged and cationic linkages can be enhanced between, approximately, five to 100 fold in cell free translation assays. A preferred antisense oligomer of the invention (M1/M2-AUG) in a form that contains three cationic linkages, as illustrated in FIG. 1B and FIG. 2, interspersed throughout the oligomer is shown as SEQ ID NO: 13 in Table 2 below. A series of exemplary antisense oligomers that target the M1/M2 AUG and contain three interspersed cationic linkages is shown in SEQ ID NOs: 34-47.

Table 2 below shows exemplary targeting sequences, in a 5′-to-3′ orientation, that are complementary to influenza A virus. The sequences listed provide a collection of targeting sequences from which targeting sequences may be selected, according to the general class rules discussed above. Although the listed targeting sequences could be used for any antisense analog oligonucleotide chemistry (e.g., PNA, LNA or 2′-OMe) the sequences in Table 2 are preferred for use as PMO antisense oligomers. SEQ ID NOs:12-22, 25-29 and 34-47 are antisense to the positive strand (mRNA or vcRNA) of the virus whereas SEQ ID NOs:23 and 24 are antisense to the minus strand (vRNA). Thus, for example, in selecting a target against the 3′ terminus of the minus strand of the M1/M2 encoding segment (segment 7 of influenza A) SEQ ID NO: 4, or a portion of the sequence effective to block the function of the 3′ terminus of the minus strand can be selected. SEQ ID NOs: 12-29 and 34-47 target the M1/M2 segment of Influenza A subtype H1N1 (S-OIV) whereas SEQ ID NOs: 30-33 target the PB1 or NP segments as indicated.

TABLE 2 Exemplary Antisense Targeting Sequences Target SEQ. ID PMO Name Ncts. Antisense Oligomer (5′ to 3′) NO. M1/M2-AUG 22-41 CGGTTAGAAGACTCATCTTT 12 M1/M2-AUGplus 22-41 CGGT+TAGAAGAC+TCATC+TTT 13 M1/M2-AUG.20.17 17-36 AGAAGACTCATCTTTCAATA 14 M1/M2-AUG.20.19 19-38 TTAGAAGACTCATCTTTCAA 15 M1/M2-AUG.20.24 24-43 CTCGGTTAGAAGACTCATCT 16 M1/M2-vcTerm.25.3  3-27 ATCTTTCAATATCTACCTGCTTTTG 17 M1/M2-vcTerm.25.6  6-30 CTCATCTTTCAATATCTACCTGCTT 18 M1/M2-AUG.25.19 19-43 CTCGGTTAGAAGACTCATCTTTCAA 19 M1/M2-AUG.25.21 21-45 ACCTCGGTTAGAAGACTCATCTTTC 20 M1/M2-AUG.25.24 24-48 TCGACCTCGGTTAGAAGACTCATCT 21 M1/M2-AUG.25.26 26-50 TTTCGACCTCGGTTAGAAGACTCAT 22 M1/M2-3′vTerm.25.1003 1003-1027 AGCAAAAGCAGGTAGATATTGAAAA 23 M1/M2-3′vTerm.25.997  997-1021 AGCAGGTAGATATTGAAAAATGAGT 24 M1/M2-SA.24.738 738-761 CTCCCATTCGCTTCTGGTAGGCCT 25 M1/M2-SA.24.740 740-762 CACTCCCATTCGCTTCTGGTAGGC 26 M1/M2-SA.24.742 742-764 TGCACTCCCATTCGCTTCTGGTAG 27 M1/M2-SA.24.744 744-766 TCTGCACTCCCATTCGCTTCTGGT 28 M1/M2-SA.24.746 746-768 CATCTGCACTCCCATTCGCTTCTG 29 NP-v3′ AGCAAAAGCAGIGTAGATAATC 30 NP-v3′plus AGCAAAAGCAGIG+TAGA+TAA+TC 31 PB1-AUG+15 CGGATTGACATCCATTCAAATG 32 PB1-AUG+15plus CGGAT+TGACA+TCCAT+TCAAATG 33 M1/M2-AUG.20.6+  6-25 CTT+TCAA+TATCTACC+TGCTT 34 M1/M2-AUG.20.11+ 11-30 C+TCA+TCTTTCAA+TATCTACC 35 M1/M2-AUG.20.12+ 12-31 AC+TCA+TCTTTCAA+TATCTAC 36 M1/M2-AUG.20.13+ 13-32 GAC+TCA+TCTTTCAA+TATCTA 37 M1/M2-AUG.20.14+ 14-33 AGAC+TCA+TCTTTCAA+TATCT 38 M1/M2-AUG.20.15+ 15-34 AAGAC+TCA+TCTTTCAA+TATC 39 M1/M2-AUG.20.16+ 16-35 GAAGAC+TCA+TCTTTCAA+TAT 40 M1/M2-AUG.20.17+ 17-36 AGAAGAC+TCA+TCTTTCAA+TA 41 M1/M2-AUG.20.18+ 18-37 TAGAAGAC+TCA+TCTTTCAA+T 42 M1/M2-AUG.20.19+ 19-38 T+TAGAAGAC+TCA+TCTTTCAA 43 M1/M2-AUG.20.20+ 20-39 GT+TAGAAGAC+TCA+TCTTTCA 44 M1/M2-AUG.20.23+ 23-42 TCGGT+TAGAAGAC+TCA+TCTT 45 M1/M2-AUG.20.25+ 25-44 CCTCGGT+TAGAAGAC+TCA+TC 46 M1/M2-AUG.20.27+ 27-46 GACC+TCGGT+TAGAAGAC+TCA 47 Antisense Oligonucleotide Compounds

As detailed above, the antisense oligonucleotide (the term “antisense” indicates that the compound is targeted against either the virus' positive-sense strand RNA or negative-sense or minus-strand) typically comprises a base sequence targeting a region that includes one or more of the following; 1) the 5′ or 3′ terminal 25 bases of the negative sense viral RNA; 2) the terminal 30 bases of the 5′ or 3′ terminus of the positive sense vcRNA; 3) 45 bases surrounding the AUG start codons of viral mRNA and/or; 4) 50 bases surrounding the splice donor or acceptor sites of influenza mRNAs subject to alternative splicing. In addition, the oligomer is able to effectively target infecting viruses, when administered to a host cell, e.g., in an infected mammalian subject, such as by reducing target protein expression (e.g., M1 or M2 or both), by reducing viral replication, or both. This requirement is typically met when the oligomer compound (a) has the ability to be actively taken up by mammalian cells, and (b) once taken up, form a duplex with the target RNA with a Tm greater than about 45° C.

In certain embodiments, the oligomer backbone may be substantially uncharged, and, preferably, may be recognized as a substrate for active or facilitated transport across the cell membrane. The ability of the oligomer to form a stable duplex with the target RNA may also relate to other features of the oligomer backbone, including the length and degree of complementarity of the antisense oligomer with respect to the target, the ratio of G:C to A:T base matches, and the positions of any mismatched bases. The ability of the antisense oligomer to resist cellular nucleases may promote survival and ultimate delivery of the agent to the cell cytoplasm. Exemplary antisense oligomer targeting sequences of the invention using the PMO backbone chemistry are listed above in Table 2. Targeting sequences using alternative chemistries are listed below in Tables 3 and 4 for PNA and LNA chemistries, respectively. In general, PNA and LNA chemistries utilize shorter targeting oligomers due to their relatively high target binding strength compared to PMO and 2′O-Me oligomers.

Peptide nucleic acids (PNAs) are analogs of DNA in which the backbone is structurally homomorphous with a deoxyribose backbone, consisting of N-(2-aminoethyl) glycine units to which pyrimidine or purine bases are attached. PNAs containing natural pyrimidine and purine bases hybridize to complementary oligonucleotides obeying Watson-Crick base-pairing rules, and mimic DNA in terms of base pair recognition (Egholm, Buchardt et al. 1993). The backbone of PNAs is formed by peptide bonds rather than phosphodiester bonds, making them well-suited for antisense applications (see structure below). The backbone is uncharged, resulting in PNA/DNA or PNA/RNA duplexes that exhibit greater than normal thermal stability. PNAs are not recognized by nucleases or proteases.

PNAs can be produced synthetically using any technique known in the art. A PNA is a DNA analog in which a polyamide backbone replaces the traditional phosphate ribose ring of DNA, as illustrated below.

Despite a radical structural change to the natural structure, PNAs are capable of sequence-specific binding in a helix form to DNA or RNA. Characteristics of PNAs include a high binding affinity to complementary DNA or RNA, a destabilizing effect caused by single-base mismatch, resistance to nucleases and proteases, hybridization with DNA or RNA independent of salt concentration and triplex formation with homopurine DNA. PANAGENE™ has developed its proprietary Bts PNA monomers (Bts; benzothiazole-2-sulfonyl group) and proprietary oligomerization process. The PNA oligomerization using Bts PNA monomers is composed of repetitive cycles of deprotection, coupling and capping. Exemplary patents to this technology include U.S. Pat. Nos. 6,969,766, 7,211,668, 7,022,851, 7,125,994, 7,145,006 and 7,179,896. Representative United States patents that teach the preparation of PNA compounds include, but are not limited to, U.S. Pat. Nos. 5,539,082; 5,714,331; and 5,719,262, each of which is herein incorporated by reference. Further teaching of PNA compounds can be found in Nielsen et al., Science, 254:1497-1500, 1991.

Exemplary PNA compounds for practicing the invention are listed below in Table 3. These oligonucleotides can be prepared essentially according to the procedures set forth in the references cited herein.

TABLE 3 Exemplary PNA Antisense Targeting Sequences Target SEQ. ID PNA Name Ncts. Antisense Oligomer (5′ to 3′) NO. PNA-M1-AUG.20.22 22-41 CGGTTAGAAGACTCATCTTT 48 PNA-M1-AUG.18.24 24-41 CGGTTAGAAGACTCATCT 49 PNA-M1-AUG.16.26 16-41 CGGTTAGAAGACTCAT 50 PNA-M1-AUG.20.17 17-36 AGAAGACTCATCTTTCAATA 51 PNA-M1-AUG.20.19 19-38 TTAGAAGACTCATCTTTCAA 52 PNA-M1-AUG.20.24 24-43 CTCGGTTAGAAGACTCATCT 53 PNA-M1-vcTerm.20.3  3-22 TCAATATCTACCTGCTTTTG 54 PNA-M1-vcTerm.20.6  6-25 CTTTCAATATCTACCTGCTT 55 PNA-M1-3′vTrm.20.1008 1003-1027 AGCAAAAGCAGGTAGATATT 56 PNA-M1-3′vTrm.20.1002 1002-1021 AGCAGGTAGATATTGAAAAA 57 M1-SA.20.738 738-757 CATTCGCTTCTGGTAGGCCT 58 M1/M2-SA.24.740 740-759 CCCATTCGCTTCTGGTAGGC 59 M1/M2-SA.24.742 742-761 CTCCCATTCGCTTCTGGTAG 60 M1/M2-SA.24.744 744-763 CACTCCCATTCGCTTCTGGT 61 M1/M2-SA.24.746 746-765 TGCACTCCCATTCGCTTCTG 62

Oligonucleotide compounds of the present invention may also contain “locked nucleic acid” subunits (LNAs). The structures of LNAs can be found, for example, in Wengel, et al., Chemical Communications (1998) 455; Tetrahedron (1998) 54:3607, and Accounts of Chem. Research (1999) 32:301); Obika, et al., Tetrahedron Letters (1997) 38:8735; (1998) 39:5401, and Bioorganic Medicinal Chemistry (2008) 16:9230. Non-limiting, exemplary LNA structures are illustrated below:

Compounds of the invention may incorporate one or more LNAs; in some cases, the compounds may be entirely composed of LNAs. Methods for the synthesis of individual LNA nucleoside subunits and their incorporation into oligonucleotides are known in the art: U.S. Pat. Nos. 7,572,582, 7,569,575, 7,084,125, 7,060,809, 7,053,207, 7,034,133, 6,794,499, and 6,670,461. Typical intersubunit linkers include phosphodiester and phosphorothioate moieties; alternatively, non-phosphorous containing linkers may be employed. A preferred embodiment is an LNA containing compound where each LNA subunit is separated by a DNA subunit. Further preferred compounds are composed of alternating LNA and DNA subunits where the intersubunit linker is phosphorothioate.

The following compounds are prepared essentially according to the procedures set forth in the references cited above. Exemplary compounds containing LNA subunits (LNAs are capitalized, DNAs are in lower case, and the sequences are read from 5′ to 3′) are shown below in Table 4.

TABLE 4 Exemplary LNA Antisense Targeting Sequences LNA Name Sequence (5′-3′) SEQ ID NO LNA-AUG1 CgGtTaGaAgAcTcAtCtTt 63 LNA-AUG2 GaAgAcTcAt 64 LNA-AUG3 GAaGaCtCAT 65 LNA-AUG4 GAAGACTCAT 66 LNA-AUG5 AGAAGACTCA 67 LNA-AUG6 TAGAAGACTC 68 LNA-AUG7 TTAGAAGACT 69 LNA-AUG8 AAGACTCATC 70 LNA-AUG9 AGACTCATCT 71 LNA-AUG10 gAcTcAtCtT 72 LNA-AUG11 ACTCATCTTT 73 LNA-AUG12 CgGtTaGaAgAcTcAt 74 LNA-AUG13 GtTaGaAgAcTcAt 75 LNA-AUG14 GTTAGAAGACT 76 LNA-AUG15 CATCTTTAAAT 77 LNA-AUG16 CaTcTtTaAaTaTcTaC 78 LNA-AUG17 CGGTTAGAAGACTCAT 79 LNA-AUG18 GGTTAGAAGACTCATC 80 LNA-AUG19 GTTAGAAGACTCATCT 81 LNA-AUG20 TTAGAAGACTCATCTT 82 LNA-AUG21 TAGAAGACTCATCTTT 83 LNA-AUG22 AGAAGACTCATCTTTA 84 LNA-AUG23 GAAGACTCATCTTTAA 85 LNA-AUG24 AAGACTCATCTTTAAA 86 LNA-AUG25 AGACTCATCTTTAAAT 87 LNA-AUG26 GACTCATCTTTAAATA 88 LNA-AUG27 ACTCATCTTTAAATAT 89 LNA-AUG28 CTCATCTTTAAATATC 90 LNA-AUG29 TCATCTTTAAATATCT 91 LNA-AUG30 CATCTTTAAATATCTA 92 LNA-AUG31 ATCTTTAAATATCTAC 93 LNA-AUG32 TCTTTAAATATCTACC 94 LNA-AUG33 CTTTAAATATCTACCA 95 LNA-AUG34 TTTAAATATCTACCAG 96 LNA-AUG35 CgGgTaGaAgAcTcAt 97 LNA-AUG36 GgTtAgAaGaCtCaTc 98 LNA-AUG37 GtTaGaAgAcTcAtCt 99 LNA-AUG38 TtAgAaGaCtCaTcTt 100 LNA-AUG39 TaGaAgAcTcAtCtTt 101 LNA-AUG40 AgAaGaCtCaTcTtTa 102 LNA-AUG41 GaAgAcTcAtCtTtAa 103 LNA-AUG42 AaGaCtCaTcTtTaAa 104 LNA-AUG43 AgAcTcAtCtTtAaAt 105 LNA-AUG44 GaCtCaTcTtTaAaTa 106 LNA-AUG45 AcTcAtCtTtAaAtAt 107 LNA-AUG46 CtCaTcTaTaAaTaTc 108 LNA-AUG47 TcAtCtTtAaAtAtCt 109 LNA-AUG48 CaTcTtTaAaTaTcTa 110 LNA-AUG49 AtCtTtAaAtAtCtAc 111 LNA-AUG50 TcTtTaAaTaTcTaCc 112 LNA-AUG51 CtTtAaAtAtCtAcCa 113 LNA-AUG52 TtTaAaTaTcTaCcAg 114

A preferred oligomer structure employs morpholino-based subunits bearing base-pairing moieties, joined by uncharged linkages, as described above. Especially preferred is a substantially uncharged phosphorodiamidate-linked morpholino oligomer. Morpholino oligonucleotides, including antisense oligomers, are detailed, for example, in co-owned U.S. Pat. Nos. 5,698,685, 5,217,866, 5,142,047, 5,034,506, 5,166,315, 5,185,444, 5,521,063, and 5,506,337, and in PCT application No. US2008/012804, all of which are expressly incorporated by reference.

Certain properties of the morpholino-based subunits include: the ability to be linked in a oligomeric form by stable, uncharged backbone linkages; the ability to support a nucleotide base (e.g., adenine, cytosine, guanine or uracil) such that the polymer formed can hybridize with a complementary-base target nucleic acid, including target RNA, with high Tm, even with oligomers as short as 10-14 bases; the ability of the oligomer to be actively transported into mammalian cells; and the ability of the oligomer:RNA heteroduplex to resist RNase degradation.

Examples of morpholino oligonucleotides having phosphorus-containing backbone linkages are illustrated in FIGS. 1A-1C. Especially preferred is a phosphorodiamidate-linked morpholino oligonucleotide, as shown in FIG. 1B, which is modified, in accordance with one aspect of the present invention, to contain positively charged groups at preferably 10%-50% of its backbone linkages. Morpholino oligonucleotides with uncharged backbone linkages, including antisense oligonucleotides, are detailed, for example, in (Summerton and Weller, 1997) and in co-owned U.S. Pat. Nos. 5,698,685, 5,217,866, 5,142,047, 5,034,506, 5,166,315, 5,185,444, 5,521,063, and 5,506,337, and in PCT application No. US2008/012804, all of which are incorporated by reference. Exemplary morpholino oligonucleotides with charged backbone linkages and/or modified terminal groups, including antisense oligonucleotides, are detailed in PCT application No. US2007/011435; co-pending U.S. Provisional Application No. 61/349,783; and co-pending U.S. Provisional Application No. 61/361,878, each of which is incorporated by reference in its entirety.

Properties of the morpholino-based subunits include: 1) the ability to be linked in a oligomeric form by stable, uncharged or positively charged backbone linkages; 2) the ability to support a nucleotide base (e.g., adenine, cytosine, guanine, thymidine, uracil and hypoxanthine) such that the polymer formed can hybridize with a complementary-base target nucleic acid, including target RNA, Tm values above about 45° C. in relatively short oligonucleotides (e.g., 10-15 bases); 3) the ability of the oligonucleotide to be actively or passively transported into mammalian cells; and 4) the ability of the antisense oligonucleotide:RNA heteroduplex to resist RNase and RNaseH degradation, respectively.

Exemplary backbone structures for antisense oligonucleotides of the claimed subject matter include the morpholino subunit types shown in FIGS. 1D-1G, each linked by an uncharged or positively charged, phosphorus-containing subunit linkage. FIG. 1D shows a phosphorus-containing linkage which forms the five atom repeating-unit backbone, where the morpholino rings are linked by a 1-atom phosphoamide linkage. FIG. 1E shows a linkage which produces a 6-atom repeating-unit backbone. In this structure, the atom Y linking the 5′ morpholino carbon to the phosphorus group may be sulfur, nitrogen, carbon or, preferably, oxygen. The X moiety pendant from the phosphorus may be fluorine, an alkyl or substituted alkyl, an alkoxy or substituted alkoxy, a thioalkoxy or substituted thioalkoxy, or unsubstituted, monosubstituted, or disubstituted nitrogen, including cyclic structures, such as morpholines or piperidines. Alkyl, alkoxy and thioalkoxy preferably include 1-6 carbon atoms. The Z moieties are sulfur or oxygen, and are preferably oxygen.

The linkages shown in FIGS. 1F and 1G are designed for 7-atom unit-length backbones. In structure 1F, the X moiety is as in Structure 1E, and the Y moiety may be methylene, sulfur, or, preferably, oxygen. In Structure 1G, the X and Y moieties are as in Structure 1E. Particularly preferred morpholino oligonucleotides include those composed of morpholino subunit structures of the form shown in FIG. 1E, where X═NH₂, N(CH₃)₂, or 1-piperazine or other charged group, Y═O, and Z═O.

As noted above, the substantially uncharged oligonucleotide may be modified, in accordance with an aspect of the invention, to include charged linkages, e.g., up to about 1 per every 2-5 uncharged linkages, such as about 4-5 per every 10 uncharged linkages. In certain embodiments, optimal improvement in antisense activity may be seen when about 25% of the backbone linkages are cationic. In certain embodiments, enhancement may be seen with a small number e.g., 10-20% cationic linkages, or where the number of cationic linkages are in the range 50-80%, such as about 60%.

Additional experiments conducted in support of the present invention indicate that the enhancement seen with added cationic backbone charges may, in some cases, be further enhanced by distributing the bulk of the charges close of the “center-region” backbone linkages of the antisense oligonucleotide, e.g., in a 20-mer oligonucleotide with 8 cationic backbone linkages, having at least 70% of these charged linkages localized in the 10 centermost linkages.

In certain embodiments, the antisense compounds can be prepared by stepwise solid-phase synthesis, employing methods detailed in the references cited above, and below with respect to the synthesis of oligonucleotides having a mixture or uncharged and cationic backbone linkages. In some cases, it may be desirable to add additional chemical moieties to the antisense compound, e.g., to enhance pharmacokinetics or to facilitate capture or detection of the compound. Such a moiety may be covalently attached, typically to a terminus of the oligomer, according to standard synthetic methods. For example, addition of a polyethyleneglycol moiety or other hydrophilic polymer, e.g., one having 10-100 monomeric subunits, may be useful in enhancing solubility. One or more charged groups, e.g., anionic charged groups such as an organic acid, may enhance cell uptake.

A reporter moiety, such as fluorescein or a radiolabeled group, may be attached for purposes of detection. Alternatively, the reporter label attached to the oligomer may be a ligand, such as an antigen or biotin, capable of binding a labeled antibody or streptavidin. In selecting a moiety for attachment or modification of an antisense compound, it is generally of course desirable to select chemical compounds of groups that are biocompatible and likely to be tolerated by a subject without undesirable side effects.

As noted above, certain of the antisense compounds can be constructed to contain a selected number of cationic linkages interspersed with uncharged linkages of the type described above. The intersubunit linkages, both uncharged and cationic, preferably are phosphorus-containing linkages, having the structure:

where W is S or O, and is preferably O, X═NR¹R² or OR⁶, Y═O or NR⁷,

and each said linkage in the oligomer is selected from:

(a) uncharged linkage (a), where each of R¹, R², R⁶ and R⁷ is independently selected from hydrogen and lower alkyl;

(b1) cationic linkage (b1), where X═NR¹R² and Y═O, and NR¹R² represents an optionally substituted piperazino group, such that R¹R²═—CHRCHRN(R³)(R⁴)CHRCHR—, where

each R is independently H or CH₃,

R⁴ is H, CH₃, or an electron pair, and

R³ is selected from H, lower alkyl, e.g., CH₃, C(═NH)NH₂, Z-L-NHC(═NH)NH₂, and [C(O)CHR′NH]_(m)H, where: Z is C(O) or a direct bond, L is an optional linker up to 18 atoms in length, preferably up to 12 atoms, and more preferably up to 8 atoms in length, having bonds selected from alkyl, alkoxy, and alkylamino, R′ is a side chain of a naturally occurring amino acid or a one- or two-carbon homolog thereof, and m is 1 to 6, preferably 1 to 4;

(b2) cationic linkage (b2), where X═NR¹R² and Y═O, R¹═H or CH₃, and R²=LNR³R⁴R⁵, where L, R³, and R⁴ are as defined above, and R⁵ is H, lower alkyl, or lower (alkoxy)alkyl; and

(b3) cationic linkage (b3), where Y═NR⁷ and X═OR⁶, and R⁷=LNR³R⁴R⁵, where L, R³, R⁴ and R⁵ are as defined above, and R⁶ is H or lower alkyl;

and at least one said linkage is selected from cationic linkages (b1), (b2), and (b3).

In certain embodiments, an oligomer may include at least two consecutive linkages of type (a) (i.e. uncharged linkages). In further embodiments, at least 5% of the linkages in the oligomer are cationic linkages (i.e. type (b1), (b2), or (b3)); for example, 10% to 60%, and preferably 20-50% linkages may be cationic linkages.

In one embodiment, at least one linkage is of type (b1), where, preferably, each R is H, R⁴ is H, CH₃, or an electron pair, and R³ is selected from H, lower alkyl, e.g., CH₃, C(═NH)NH₂, and C(O)-L-NHC(═NH)NH₂. The latter two embodiments of R³ provide a guanidino moiety, either attached directly to the piperazine ring, or pendant to a linker group L, respectively. For ease of synthesis, the variable Z in R³ is preferably C(O) (carbonyl), as shown.

The linker group L, as noted above, contains bonds in its backbone selected from alkyl (e.g., —CH₂—CH₂—), alkoxy (—C—O—), and alkylamino (e.g., —CH₂—NH—), with the proviso that the terminal atoms in L (e.g., those adjacent to carbonyl or nitrogen) are carbon atoms. Although branched linkages (e.g., —CH₂—CHCH₃—) are possible, the linker is preferably unbranched. In one embodiment, the linker is a hydrocarbon linker. Such a linker may have the structure —(CH₂)_(n)—, where n is 1-12, preferably 2-8, and more preferably 2-6.

The morpholino subunits have the structure:

where Pi is a base-pairing moiety, and the linkages depicted above connect the nitrogen atom of (i) to the 5′ carbon of an adjacent subunit. The base-pairing moieties Pi may be the same or different, and are generally designed to provide a sequence which binds to a target nucleic acid.

The use of embodiments of linkage types (b1), (b2) and (b3) above to link morpholino subunits may be illustrated graphically as follows:

Preferably, all cationic linkages in the oligomer are of the same type; i.e. all of type (b1), all of type (b2), or all of type (b3).

In further embodiments, the cationic linkages are selected from linkages (b1′) and (b1″) as shown below, where (b1″) is referred to herein as a “Pip” linkage and (b1″) is referred to herein as a “GuX” linkage:

In the structures above, W is S or O, and is preferably O; each of R¹ and R² is independently selected from hydrogen and lower alkyl, and is preferably methyl; and A represents hydrogen or a non-interfering substituent on one or more carbon atoms in (b1′) and (b1″). Preferably, the ring carbons in the piperazine ring are unsubstituted; however, they may include non-interfering substituents, such as methyl or fluorine. Preferably, at most one or two carbon atoms is so substituted. In further embodiments, at least 10% of the linkages are of type (b1′) or (b1″); for example, 10%-60% and preferably 20% to 50%, of the linkages may be of type (b1′) or (b1″).

In certain embodiments, the oligomer contains no linkages of the type (b1′) above. Alternatively, the oligomer contains no linkages of type (b1) where each R is H, R³ is H or CH₃, and R⁴ is H, CH₃, or an electron pair.

The morpholino subunits may also be linked by non-phosphorus-based intersubunit linkages, as described further below, where at least one linkage is modified with a pendant cationic group as described above.

Other oligonucleotide analog linkages which are uncharged in their unmodified state but which could also bear a pendant amine substituent could be used. For example, a 5′ nitrogen atom on a morpholino ring could be employed in a sulfamide linkage or a urea linkage (where phosphorus is replaced with carbon or sulfur, respectively) and modified in a manner analogous to the 5′-nitrogen atom in structure (b3) above.

Oligomers having any number of cationic linkages are provided, including fully cationic-linked oligomers. Preferably, however, the oligomers are partially charged, having, for example, 10%-80%. In preferred embodiments, about 10% to 60%, and preferably 20% to 50% of the linkages are cationic.

In one embodiment, the cationic linkages are interspersed along the backbone. The partially charged oligomers preferably contain at least two consecutive uncharged linkages; that is, the oligomer preferably does not have a strictly alternating pattern along its entire length.

Also considered are oligomers having blocks of cationic linkages and blocks of uncharged linkages; for example, a central block of uncharged linkages may be flanked by blocks of cationic linkages, or vice versa. In one embodiment, the oligomer has approximately equal-length 5′, 3′ and center regions, and the percentage of cationic linkages in the center region is greater than about 50%, preferably greater than about 70%.

Oligomers for use in antisense applications generally range in length from about 10 to about 40 subunits, more preferably about 10 to 30 subunits, and typically 15-25 bases. For example, an oligomer of the invention having 19-20 subunits, a useful length for an antisense compound, may ideally have two to ten, e.g., four to eight, cationic linkages, and the remainder uncharged linkages. An oligomer having 14-15 subunits may ideally have two to seven, e.g., 3, 4, or 5, cationic linkages and the remainder uncharged linkages.

Each morpholino ring structure supports a base pairing moiety, to form a sequence of base pairing moieties which is typically designed to hybridize to a selected antisense target in a cell or in a subject being treated. The base pairing moiety may be a purine or pyrimidine found in native DNA or RNA (e.g., A, G, C, T or U) or an analog, such as hypoxanthine (the base component of the nucleoside inosine) or 5-methyl cytosine.

Peptide Transporters

In certain embodiments, the antisense compounds of the invention may include an oligonucleotide moiety conjugated to an arginine-rich peptide transport moiety effective to enhance transport of the compound into cells. The transport moiety may be attached to a terminus of the oligomer, as shown, for example, in FIG. 1C. The peptide transport moiety preferably comprises 6 to 16 subunits selected from X′ subunits, Y′ subunits, and Z′ subunits, where

(a) each X′ subunit independently represents lysine, arginine or an arginine analog, said analog being a cationic α-amino acid comprising a side chain of the structure R¹N═C(NH₂)R², where R¹ is H or R; R² is R, NH₂, NHR, or NR₂, where R is lower alkyl or lower alkenyl and may further include oxygen or nitrogen; R¹ and R² may together form a ring; and the side chain is linked to said amino acid via R¹ or R²;

(b) each Y′ subunit independently represents a neutral amino acid —C(O)—(CHR)_(n)—NH—, where n is 2 to 7 and each R is independently H or methyl; and

(c) each Z′ subunit independently represents an α-amino acid having a neutral aralkyl side chain;

wherein the peptide comprises a sequence represented by one of (X′Y′X′)_(p), (X′Y′)_(m), (X′)_(m), and (X′Z′Z′)_(p), where p is 2 to 5 and m is 2 to 9. Certain embodiments include various combinations selected independently from (X′Y′X′)_(p), (X′Y′)_(m), (X′)_(m), and/or (X′Z′Z′)_(p), including, for example, peptides having the sequence (X′Y′X′)(X′Z′Z′)(X′Y′X′)(X′Z′Z′) (SEQ ID NO:129).

In selected embodiments, for each X′, the side chain moiety is guanidyl, as in the amino acid subunit arginine (Arg). In further embodiments, each Y′ is —CO—(CH₂)_(n)—CHR—NH—, where n is 2 to 7 and R is H. For example, when n is 5 and R is H, Y′ is a 6-aminohexanoic acid subunit, abbreviated herein as Ahx; when n is 2 and R is H, Y′ is a β-alanine subunit, abbreviated herein as B. Certain embodiments relate to carrier peptides having a combination of different neutral amino acids, including, for example, peptides comprising the sequence -RAhxRRBRRAhxRRBRAhxB- (SEQ ID NO:124), which contains both β-alanine and 6-aminohexanoic acid.

Preferred peptides of this type include those comprising arginine dimers alternating with single Y′ subunits, where Y′ is preferably Ahx. Examples include peptides having the formula (RY′R)_(p) or the formula (RRY′_(p), where Y′ is preferably Ahx. In one embodiment, Y′ is a 6-aminohexanoic acid subunit, R is arginine and p is 4.

Certain embodiments include various linear combinations of at least two of (RY′R)_(p) and (RRY′)_(p), including, for example, illustrative peptides having the sequence (RY′R)(RRY′)(RY′R)(RRY′) (SEQ ID NO:130), or (RRY′)(RY′R)(RRY′) (SEQ ID NO:131). Other combinations are contemplated. In a further illustrative embodiment, each Z′ is phenylalanine, and m is 3 or 4.

The conjugated peptide is preferably linked to a terminus of the oligomer via a linker Ahx-B, where Ahx is a 6-aminohexanoic acid subunit and B is a (3-alanine subunit, as shown, for example, in FIG. 1C. Alternative linkers between the peptide and oligomer include glycine and cysteine. These and related linkers may be conjugated through an amide or disulfide bond.

In selected embodiments, for each X′, the side chain moiety is independently selected from the group consisting of guanidyl (HN═C(NH₂)NH—), amidinyl (HN═C(NH₂)C<), 2-aminodihydropyrimidyl, 2-aminotetrahydropyrimidyl, 2-aminopyridinyl, and 2-aminopyrimidonyl, and it is preferably selected from guanidyl and amidinyl. In one embodiment, the side chain moiety is guanidyl, as in the amino acid subunit arginine (Arg).

In certain embodiments, the Y′ subunits may be either contiguous, in that no X′ subunits intervene between Y′ subunits, or interspersed singly between X′ subunits. In certain embodiments, the linking subunit may be between Y′ subunits. In one embodiment, the Y′ subunits are at a terminus of the transporter; in other embodiments, they are flanked by X′ subunits. In further preferred embodiments, each Y′ is —CO—(CH₂)_(n)—CHR—NH—, where n is 2 to 7 and R is H. For example, when n is 5 and R is H, Y′ is a 6-aminohexanoic acid subunit, abbreviated herein as Ahx.

In selected embodiments of this group, each X′ comprises a guanidyl side chain moiety, as in an arginine subunit. Preferred peptides of this type include those comprising arginine dimers alternating with single Y′ subunits, where Y′ is preferably Ahx. Examples include peptides having the formula (RY′R)₄ (SEQ ID NO:132) or the formula (RRY′)₄ (SEQ ID NO:133), where Y′ is preferably Ahx. In the latter case, the nucleic acid analog is preferably linked to a terminal Y′ subunit, preferably at the C-terminus, as shown, for example, in FIG. 1C. One exemplary linker is of the structure AhxB, where Ahx is a 6-aminohexanoic acid subunit and B is a β-alanine subunit. Alternative linkers include cysteine and glycine.

The transport moieties as described herein have been shown to greatly enhance cell entry of attached oligomers, relative to uptake of the oligomer in the absence of the attached transport moiety, and relative to uptake by an attached transport moiety lacking the hydrophobic subunits Y′. Such enhanced uptake is preferably evidenced by at least a two-fold increase, and preferably a four-fold increase, in the uptake of the compound into mammalian cells relative to uptake of the agent by an attached transport moiety lacking the hydrophobic subunits Y′. Uptake is preferably enhanced at least twenty fold, and more preferably forty fold, relative to the unconjugated compound.

A further benefit of the transport moiety is its expected ability to stabilize a duplex between an antisense compound and its target nucleic acid sequence, presumably by virtue of electrostatic interaction between the positively charged transport moiety and the negatively charged nucleic acid. The number of charged subunits in the transporter is less than 14, as noted above, and preferably between 8 and 11.

The use of arginine-rich peptide transporters (i.e., cell-penetrating peptides) are particularly useful in practicing certain embodiments of the present invention. Certain peptide transporters have been shown to be highly effective at delivery of antisense compounds into primary cells including hematopoietic and muscle cells (Marshall, Oda et al. 2007; Jearawiriyapaisarn, Moulton et al. 2008; Wu, Moulton et al. 2008). Furthermore, compared to other known peptide transporters such as Penetratin and the Tat peptide, the peptide transporters described herein, when conjugated to an antisense PMO, demonstrate an enhanced ability to alter splicing of several gene transcripts (Marshall, Oda et al. 2007). Exemplary peptides in these studies include P007 (SEQ ID NO:118), CP04057 (SEQ ID NO:123), and CP06062 (SEQ ID NO:124).

Exemplary peptide transporters, including linkers (B, AhxB, C, or G) are given below in Table 5. In certain embodiments, the exemplary peptide transporters listed in Table 5 can be conjugated to PMO through disulfide or amide linkages.

TABLE 5 Exemplary Peptide Transporters Peptide Sequence (N-terminal to C-terminal) SEQ ID NO: rTAT RRRQRRKKRC 115 R₉F₂C RRRRRRRRRFFC 116 R₅F₂R₄C RRRRRFFRRRRC 117 (RAhxR)₄AhxB; (P007) RAhxRRAhxRRAhxRRAhxRAhxB 118 R₈C RRRRRRRRC 119 R₉C RRRRRRRRRC 120 R₈G RRRRRRRRG 121 R₉G RRRRRRRRRG 122 (RAhxR)₅AhxB (CP04057) RAhxRRAhxRRAhxRRAhxRRAhxRAhxB 123 (RAhxRRBR)₂AhxB; (CP06062) RAhxRRBRRAhxRRBRAhxB 124 (RAR)₄F₂C RARRARRARRARFFC 125 (RGR)₄F₂C RGRRGRRGRRGRFFC 126 R₉F₂G RRRRRRRRRFFG 127 R₉F₂XB RRRRRRRRRFFAhxB 128 RNA Interference Agents

The influenza target regions described herein (e.g., M1, M2; SEQ ID NOS:1-11) may also be targeted by a variety of RNA interference-based methods. RNA interference (RNAi) is an evolutionarily conserved gene-silencing mechanism, originally discovered in studies of the nematode Caenorhabditis elegans (Lee et al., Cell 75:843, 1993; Reinhart et al., Nature 403:901, 2000). It may be triggered by introducing dsRNA into cells expressing the appropriate molecular machinery, which then degrades the corresponding endogenous mRNA. The mechanism involves conversion of dsRNA into short RNAs that direct ribonucleases to homologous mRNA targets (summarized, for example, by Ruvkun, Science 2294:797, 2001).

In certain embodiments, the methods provided herein may utilize double-stranded ribonucleic acid (dsRNA) molecules as modulating agents, for reducing influenza virus replication, such as by interfering with M1 or M2 protein expression. dsRNAs generally comprise two single strands. One strand of the dsRNA comprises a nucleotide sequence that is substantially identical to a portion of the target gene or target region (the “sense” strand), and the other strand (the “complementary” or “antisense” strand) comprises a sequence that is substantially complementary to a portion of the target region. The strands are sufficiently complementary to hybridize to form a duplex structure. In certain embodiments, the complementary RNA strand may be less than 30 nucleotides, less than 25 nucleotides in length, or even 19 to 24 nucleotides in length. In certain aspects, the complementary nucleotide sequence may be 20-23 nucleotides in length, or 22 nucleotides in length.

In certain embodiments, at least one of the RNA strands comprises a nucleotide overhang of 1 to 4 nucleotides in length. In other embodiments, the dsRNA may further comprise at least one chemically modified nucleotide. In certain aspects, a dsRNA comprising a single-stranded overhang of 1 to 4 nucleotides may comprise a molecule wherein the unpaired nucleotide of the single-stranded overhang that is directly adjacent to the terminal nucleotide pair contains a purine base. In other aspects, the last complementary nucleotide pairs on both ends of a dsRNA are a G-C pair, or, at least two of the last four terminal nucleotide pairs are G-C pairs.

Certain embodiments of the present invention may comprise micro RNAs. Micro-RNAs represent a large group of small RNAs produced naturally in organisms, some of which regulate the expression of target genes. Micro-RNAs are formed from an approximately 70 nucleotide single-stranded hairpin precursor transcript by Dicer. (V. Ambros et al. Current Biology 13:807, 2003). Micro-RNAs are not translated into proteins, but instead bind to specific messenger RNAs, thereby blocking translation. It is thought that micro-RNAs base-pair imprecisely with their targets to inhibit translation. Certain micro-RNAs may be transcribed as hairpin RNA precursors, which are then processed to their mature forms by Dicer enzyme.

In certain embodiments, the modulating agent, or RNAi oligonucleotide, is single stranded. In other embodiments, the modulating agent, or RNAi oligonucleotide, is double stranded. Certain embodiments may also employ short-interfering RNAs (siRNA). In certain embodiments, the first strand of the double-stranded oligonucleotide contains two more nucleoside residues than the second strand. In other embodiments, the first strand and the second strand have the same number of nucleosides; however, the first and second strands are offset such that the two terminal nucleosides on the first and second strands are not paired with a residue on the complimentary strand. In certain instances, the two nucleosides that are not paired are thymidine resides.

In instances when the modulating agent comprises siRNA, the agent should include a region of sufficient homology to the target region, and be of sufficient length in terms of nucleotides, such that the siRNA agent, or a fragment thereof, can mediate down regulation of the target RNA. It will be understood that the term “ribonucleotide” or “nucleotide” can, in the case of a modified RNA or nucleotide surrogate, also refer to a modified nucleotide, or surrogate replacement moiety at one or more positions. Thus, an siRNA agent is or includes a region which is at least partially complementary to the target RNA. It is not necessary that there be perfect complementarity between the siRNA agent and the target, but the correspondence must be sufficient to enable the siRNA agent, or a cleavage product thereof, to direct sequence specific silencing, such as by RNAi cleavage of the target RNA. Complementarity, or degree of homology with the target strand, is most critical in the antisense strand. While perfect complementarity, particularly in the antisense strand, is often desired some embodiments include one or more but preferably 10, 8, 6, 5, 4, 3, 2, or fewer mismatches with respect to the target RNA. The mismatches are most tolerated in the terminal regions, and if present are preferably in a terminal region or regions, e.g., within 6, 5, 4, or 3 nucleotides of the 5′ and/or 3′ terminus. The sense strand need only be sufficiently complementary with the antisense strand to maintain the overall double-strand character of the molecule.

In addition, an siRNA modulating agent may be modified or include nucleoside surrogates. Single stranded regions of an siRNA agent may be modified or include nucleoside surrogates, e.g., the unpaired region or regions of a hairpin structure, e.g., a region which links two complementary regions, can have modifications or nucleoside surrogates. Modification to stabilize one or more 3′- or 5′-terminus of an siRNA agent, e.g., against exonucleases, or to favor the antisense siRNA agent to enter into RISC are also useful. Modifications can include C3 (or C6, C7, C12) amino linkers, thiol linkers, carboxyl linkers, non-nucleotidic spacers (C3, C6, C9, C12, abasic, triethylene glycol, hexaethylene glycol), special biotin or fluorescein reagents that come as phosphoramidites and that have another DMT-protected hydroxyl group, allowing multiple couplings during RNA synthesis.

siRNA agents may include, for example, molecules that are long enough to trigger the interferon response (which can be cleaved by Dicer (Bernstein et al., Nature, 409:363-366, 2001) and enter a RISC(RNAi-induced silencing complex)), in addition to molecules which are sufficiently short that they do not trigger the interferon response (which molecules can also be cleaved by Dicer and/or enter a RISC), e.g., molecules which are of a size which allows entry into a RISC, e.g., molecules which resemble Dicer-cleavage products. Molecules that are short enough that they do not trigger an interferon response are termed siRNA agents or shorter RNAi agents herein. “siRNA agent or shorter RNAi agent” as used refers to an siRNA agent that is sufficiently short that it does not induce a deleterious interferon response in a human cell, e.g., it has a duplexed region of less than 60 but preferably less than 50, 40, or 30 nucleotide pairs. An siRNA modulating agent, or a cleavage product thereof, can down regulate a target gene, e.g., by inducing RNAi with respect to a target RNA, preferably an influenza target RNA such as M1 or M2.

Each strand of an siRNA modulating agent can be equal to or less than 35, 30, 25, 24, 23, 22, 21, or 20 nucleotides in length. The strand is preferably at least 19 nucleotides in length. For example, each strand can be between 21 and 25 nucleotides in length. Preferred siRNA agents have a duplex region of 17, 18, 19, 29, 21, 22, 23, 24, or 25 nucleotide pairs, and one or more overhangs, preferably one or two 3′ overhangs, of 2-3 nucleotides.

In addition to homology to target RNA and the ability to down regulate a target gene, an siRNA modulating agent may have one or more of the following properties: it may, despite modifications, even to a very large number, or all of the nucleosides, have an antisense strand that can present bases (or modified bases) in the proper three dimensional framework so as to be able to form correct base pairing and form a duplex structure with a homologous target RNA which is sufficient to allow down regulation of the target, e.g., by cleavage of the target RNA; it may, despite modifications, even to a very large number, or all of the nucleosides, still have “RNA-like” properties, i.e., it may possess the overall structural, chemical and physical properties of an RNA molecule, even though not exclusively, or even partly, of ribonucleotide-based content. For example, an siRNA agent can contain, e.g., a sense and/or an antisense strand in which all of the nucleotide sugars contain e.g., 2′ fluoro in place of 2′ hydroxyl. This deoxyribonucleotide-containing agent can still be expected to exhibit RNA-like properties. While not wishing to be bound by theory, the electronegative fluorine prefers an axial orientation when attached to the C2′ position of ribose. This spatial preference of fluorine can, in turn, force the sugars to adopt a C3′-endo pucker. This is the same puckering mode as observed in RNA molecules and gives rise to the RNA-characteristic A-family-type helix. Further, since fluorine is a good hydrogen bond acceptor, it can participate in the same hydrogen bonding interactions with water molecules that are known to stabilize RNA structures. Generally, it is preferred that a modified moiety at the 2′ sugar position will be able to enter into H-bonding which is more characteristic of the OH moiety of a ribonucleotide than the H moiety of a deoxyribonucleotide.

A “single strand RNAi agent” as used herein, is an RNAi agent which is made up of a single molecule. It may include a duplexed region, formed by intra-strand pairing, e.g., it may be, or include, a hairpin or pan-handle structure. Single strand RNAi modulating agents are preferably antisense with regard to the target molecule. A single strand RNAi agent should be sufficiently long that it can enter the RISC and participate in RISC mediated cleavage of a target mRNA. A single strand RNAi agent is at least 14, and more preferably at least 15, 20, 25, 29, 35, 40, or 50 nucleotides in length. It is preferably less than 200, 100, or 60 nucleotides in length.

Hairpin RNAi modulating agents may have a duplex region equal to or at least 17, 18, 19, 29, 21, 22, 23, 24, or 25 nucleotide pairs. The duplex region may preferably be equal to or less than 200, 100, or 50, in length. Certain ranges for the duplex region are 15-30, 17 to 23, 19 to 23, and 19 to 21 nucleotides pairs in length. The hairpin may have a single strand overhang or terminal unpaired region, preferably the 3′, and preferably of the antisense side of the hairpin. In certain embodiments, overhangs are 2-3 nucleotides in length.

Certain modulating agents utilized according to the methods provided herein may comprise RNAi oligonucleotides such as chimeric oligonucleotides, or “chimeras,” which contain two or more chemically distinct regions, each made up of at least one monomer unit, i.e., a nucleotide in the case of an oligonucleotide compound. These oligonucleotides typically contain at least one region wherein the oligonucleotide is modified so as to confer upon the oligonucleotide increased resistance to nuclease degradation, increased cellular uptake, and/or increased binding affinity for the target nucleic acid. Consequently, comparable results can often be obtained with shorter oligonucleotides when chimeric oligonucleotides are used, compared to phosphorothioate oligodeoxynucleotides. Chimeric oligonucleotides may be formed as composite structures of two or more oligonucleotides, modified oligonucleotides, oligonucleotides and/or oligonucleotide mimetics as described above. Such oligonucleotides have also been referred to in the art as hybrids or gapmers. Representative United States patents that teach the preparation of such hybrid structures include, but are not limited to, U.S. Pat. Nos. 5,013,830, 5,149,797, 5,220,007, 5,256,775, 5,366,878, 5,403,711, 5,491,133, 5,565,350, 5,623,065, 5,652,355, 5,652,356, 5,700,922, and 5,955,589, each of which is herein incorporated by reference. In certain embodiments, the chimeric oligonucleotide is RNA-DNA, DNA-RNA, RNA-DNA-RNA, DNA-RNA-DNA, or RNA-DNA-RNA-DNA, wherein the oligonucleotide is between 5 and 60 nucleotides in length.

In one aspect of the invention, modulating agents, such as RNAi agents, relate to an oligonucleotide comprising at least one ligand tethered to an altered or non-natural nucleobase. A large number of compounds can function as the altered base. The structure of the altered base is important to the extent that the altered base should not substantially prevent binding of the oligonucleotide to its target, e.g., mRNA. In certain embodiments, the altered base is difluorotolyl, nitropyrrolyl, nitroimidazolyl, nitroindolyl, napthalenyl, anthrancenyl, pyridinyl, quinolinyl, pyrenyl, or the divalent radical of any one of the non-natural nucleobases described herein. In certain embodiments, the non-natural nucleobase is difluorotolyl, nitropyrrolyl, or nitroimidazolyl. In certain embodiments, the non-natural nucleobase is difluorotolyl. A wide variety of ligands are known in the art and are amenable to the present invention. For example, the ligand can be a steroid, bile acid, lipid, folic acid, pyridoxal, B12, riboflavin, biotin, aromatic compound, polycyclic compound, crown ether, intercalator, cleaver molecule, protein-binding agent, or carbohydrate. In certain embodiments, the ligand is a steroid or aromatic compound. In certain instances, the ligand is cholesteryl.

In other embodiments, the RNAi agent is an oligonucleotide tethered to a ligand for the purposes of improving cellular targeting and uptake. For example, an RNAi agent may be tethered to an antibody, or antigen binding fragment thereof. As an additional example, an RNAi agent may be tethered to a specific ligand binding molecule, such as a polypeptide or polypeptide fragment that specifically binds a particular cell-surface receptor.

In other embodiments, the modulating agent comprises a non-natural nucleobase. In certain embodiments, the non-natural nucleobase is difluorotolyl, nitroimidazolyl, nitroindolyl, or nitropyrrolyl. In certain embodiments, the modulating agents provided herein relate to a double-stranded oligonucleotide sequence, wherein only one of the two strands contains a non-natural nucleobase. In certain embodiments, the modulating agents as used herein relate to a double-stranded oligonucleotide sequence, wherein both of the strands independently comprise at least one non-natural nucleobase.

In certain instances, the ribose sugar moiety that naturally occurs in nucleosides is replaced with a hexose sugar. In certain aspects, the hexose sugar is an allose, altrose, glucose, mannose, gulose, idose, galactose, talose, or a derivative thereof. In a preferred embodiment, the hexose is a D-hexose. In certain instances, the ribose sugar moiety that naturally occurs in nucleosides is replaced with a polycyclic heteroalkyl ring or cyclohexenyl group. In certain instances, the polycyclic heteroalkyl group is a bicyclic ring containing one oxygen atom in the ring. In certain instances, the polycyclic heteroalkyl group is a bicyclo[2.2.1]heptane, a bicyclo[3.2.1]octane, or a bicyclo[3.3.1]nonane. In certain embodiments, the backbone of the oligonucleotide has been modified to improve the therapeutic or diagnostic properties of the oligonucleotide compound. In certain embodiments, at least one of the bases or at least one of the sugars of the oligonucleotide has been modified to improve the therapeutic or diagnostic properties of the oligonucleotide compound. In instances when the oligonucleotide is double stranded, the two strands are complementary, partially complementary, or chimeric oligonucleotides.

Examples of modified RNAi agents envisioned for use in the methods of the present invention include oligonucleotides containing modified backbones or non-natural internucleoside linkages. As defined here, oligonucleotides having modified backbones or internucleoside linkages include those that retain a phosphorus atom in the backbone and those that do not have a phosphorus atom in the backbone. Modified oligonucleotides that do not have a phosphorus atom in their intersugar backbone can also be considered to be oligonucleotides. Specific oligonucleotide chemical modifications are described below. It is not necessary for all positions in a given compound to be uniformly modified, and in fact more than one of the following modifications may be incorporated in a single oligonucleotide compound or even in a single nucleotide thereof.

Examples of modified internucleoside linkages or backbones include, for example, phosphorothioates, chiral phosphorothioates, phosphorodithioates, phosphotriesters, aminoalkylphosphotriesters, methyl and other alkyl phosphonates including 3′-alkylene phosphonates and chiral phosphonates, phosphinates, phosphoramidates including 3′-amino phosphoramidate and aminoalkylphosphoramidates, thionophosphoramidates, thionoalkylphosphonates, thionoalklyphosphotriesters, and boranophosphates having normal 3′-5′ linkages, 2′-5′ linked analogs of these, and those having inverted polarity wherein the adjacent pairs of nucleoside units are linked 3′-5′ to 5′-3′ or 2′-5′ to 5′-2′. Various salts, mixed salts and free-acid forms are also included.

Representative United States patents that teach the preparation of the above phosphorus atom-containing linkages include, but are not limited to, U.S. Pat. Nos. 3,687,808, 4,469,863, 4,476,301, 5,023,243, 5,177,196, 5,188,897, 5,264,423, 5,276,019, 5,278,302, 5,286,717, 5,321,131, 5,399,676, 5,405,939, 5,453,496, 5,455,233, 5,466,677, 5,476,925, 5,519,126, 5,536,821, 5,541,306, 5,550,111, 5,563,253, 5,571,799, 5,587,361, 5,625,050, and 5,697,248, each of which is herein incorporated by reference.

Examples of modified internucleoside linkages or backbones that do not include a phosphorus atom therein (i.e., oligonucleotides) have backbones that are formed by short chain alkyl or cycloalkyl intersugar linkages, mixed heteroatom and alkyl or cycloalkyl intersugar linkages, or one or more short chain heteroatomic or heterocyclic intersugar linkages. These include those having morpholino linkages (formed in part from the sugar portion of a nucleoside); siloxane backbones; sulfide, sulfoxide and sulfone backbones; formacetyl and thioformacetyl backbones; methylene formacetyl and thioformacetyl backbones; alkene containing backbones; sulfamate backbones; methyleneimino and methylenehydrazino backbones; sulfonate and sulfonamide backbones; amide backbones; and others having mixed N, O, S and CH₂ component parts.

Representative United States patents that teach the preparation of the above oligonucleotides include, but are not limited to, U.S. Pat. Nos. 5,034,506, 5,166,315, 5,185,444, 5,214,134, 5,216,141, 5,235,033, 5,264,562, 5,264,564, 5,405,938, 5,434,257, 5,466,677, 5,470,967, 5,489,677, 5,541,307, 5,561,225, 5,596,086, 5,602,240, 5,610,289, 5,602,240, 5,608,046, 5,610,289, 5,618,704, 5,623,070, 5,663,312, 5,633,360, 5,677,437, and 5,677,439, each of which is herein incorporated by reference.

In other examples of oligonucleotide mimetics, both the sugar and the internucleoside linkage, i.e., the backbone, of the nucleoside units may be replaced with novel groups. The nucleobase units are maintained for hybridization with an appropriate nucleic acid target compound. One such oligonucleotide, an oligonucleotide mimetic, that has been shown to have excellent hybridization properties, is referred to as a peptide nucleic acid (PNA). In PNA compounds, the sugar-backbone of an oligonucleotide is replaced with an amide-containing backbone, in particular an aminoethylglycine backbone. The nucleobases are retained and are bound directly or indirectly to atoms of the amide portion of the backbone. Representative United States patents that teach the preparation of PNA compounds include, but are not limited to, U.S. Pat. Nos. 5,539,082, 5,714,331, and 5,719,262, each of which is herein incorporated by reference. Further teaching of PNA compounds can be found in Nielsen et al., Science, 1991, 254, 1497.

The present invention further encompasses oligonucleotides employing ribozymes. Synthetic RNA molecules and derivatives thereof that catalyze highly specific endoribonuclease activities are known as ribozymes. (See, generally, U.S. Pat. No. 5,543,508 to Haseloff et al., and U.S. Pat. No. 5,545,729 to Goodchild et al.). The cleavage reactions are catalyzed by the RNA molecules themselves. In naturally occurring RNA molecules, the sites of self-catalyzed cleavage are located within highly conserved regions of RNA secondary structure (Buzayan et al., Proc. Natl. Acad. Sci. U.S.A. 83:8859-62, 1986; Forster et al., Cell. 50:9-16, 1987). Naturally occurring autocatalytic RNA molecules have been modified to generate ribozymes which can be targeted to a particular cellular or pathogenic RNA molecule with a high degree of specificity. Thus, ribozymes serve the same general purpose as antisense oligonucleotides (i.e., modulation of expression of a specific gene) and, like oligonucleotides, are nucleic acids possessing significant portions of single-strandedness.

In certain instances, the RNAi agents for use with the methods provided herein may be modified by non-ligand group. A number of non-ligand molecules have been conjugated to oligonucleotides in order to enhance the activity, cellular distribution, cellular targeting, or cellular uptake of the oligonucleotide, and procedures for performing such conjugations are available in the scientific literature. Such non-ligand moieties have included lipid moieties, such as cholesterol (Letsinger et al., Proc. Natl. Acad. Sci. USA, 86:6553-56, 1989), cholic acid (Manoharan et al., Bioorg. Med. Chem. Lett. 4:1053, 1994), a thioether, e.g., hexyl-5-tritylthiol (Manoharan et al., Ann. N.Y. Acad. Sci., 660:306, 1992; Manoharan et al., Bioorg. Med. Chem. Let., 3:2765, 1993), a thiocholesterol (Oberhauser et al., Nucl. Acids Res., 20:533, 1992), an aliphatic chain, e.g., dodecandiol or undecyl residues (Saison-Behmoaras et al., EMBO J. 10:111, 1991; Kabanov et al., FEBS Lett. 259:327, 1990; Svinarchuk et al., Biochimie. 75:49, 1993), a phospholipid, e.g., di-hexadecyl-rac-glycerol or triethylammonium 1,2-di-O-hexadecyl-rac-glycero-3-H-phosphonate (Manoharan et al., Tetrahedron Lett., 36:3651, 1995; Shea et al., Nucl. Acids Res. 18:3777, 1990), a polyamine or a polyethylene glycol chain (Manoharan et al., Nucleosides & Nucleotides. 14:969, 1995), or adamantane acetic acid (Manoharan et al., Tetrahedron Lett. 36:3651, 1995), a palmityl moiety (Mishra et al., Biochim. Biophys. Acta. 1264:229, 1995), or an octadecylamine or hexylamino-carbonyl-oxycholesterol moiety (Crooke et al., J. Pharmacol. Exp. Ther. 277:923, 1996). Representative United States patents that teach the preparation of such oligonucleotide conjugates have been listed above. Typical conjugation protocols involve the synthesis of oligonucleotides bearing an aminolinker at one or more positions of the sequence. The amino group is then reacted with the molecule being conjugated using appropriate coupling or activating reagents. The conjugation reaction may be performed either with the oligonucleotide still bound to the solid support or following cleavage of the oligonucleotide in solution phase. Purification of the oligonucleotide conjugate by HPLC typically affords the pure conjugate.

Additional examples of modulating agents, such as RNAi oligonucleotides, may be found in U.S. Application Publication Nos. 2007/0275465, 2007/0054279, 2006/0287260, 2006/0035254, 2006/0008822, which are incorporated by reference.

Inhibition of Influenza Viral Replication

The antisense compounds detailed above are useful in inhibiting replication of single-stranded, negative-sense, segmented RNA viruses of the Orthomyxoviridae family. In one embodiment, such inhibition is effective in treating infection of a host animal by these viruses. Accordingly, the method comprises, in one embodiment, contacting a cell infected with the virus with a antisense agent effective to inhibit the replication of the specific virus. In this embodiment, the antisense agent is administered to a mammalian subject, e.g., human or domestic animal, infected with a given virus, in a suitable pharmaceutical carrier. It is contemplated that the antisense oligonucleotide arrests the growth of the RNA virus in the host. The RNA virus may be decreased in number or eliminated with little or no detrimental effect on the normal growth or development of the host.

In the present invention as described in the Examples, Phosphorodiamidate Morpholino Oligomers (PMOs), designed to hybridize to the M1/M2 gene segment of influenza A virus (i.e., segment 7), were evaluated for their ability to inhibit influenza virus production in two animal models. The PMOs were either conjugated to a short arginine-rich peptide to facilitate entry into cells or made as PMOplus™ compounds containing cationic linkages. The compounds targeted the AUG translation start-site of the M1 matrix protein (M1) and the ion channel protein (M2) both of which are expressed from the same AUG start codon using alternative splice forms of the M1/M2 mRNA.

The M1/M2-AUG targeted antisense compounds of the invention led to the inhibition of viral titer in a mouse model of H3N2 as described in Example 1. The M1/M2-AUG targeted compounds of the invention also demonstrated reduced clinical signs of flu infection and reduced viral titers in nasal washes in the ferret model of 2009H1N1 (S-OIV) pandemic swine flu as described in Example 2. Accordingly, the antisense oligonucleotides and RNAi agents exemplified herein may be used in the treatment of viral infections, mainly those attributable to single-stranded, negative-sense, segmented RNA viruses of the Orthomyxoviridae family.

Embodiments of the present invention also include combination therapies and related compositions. For instance, the antiviral (i.e., virally-targeted) antisense oligonucleotides and RNAi agents provided herein may be used in combination with host molecule-targeted antisense oligonucleotides or RNAi agents. In this regard, antisense or RNAi targeting of a host immune response gene and/or its receptor can be used to improve the immune response and thereby prevent or reduce subsequent infections, whether viral or bacterial (e.g., secondary bacterial infections). As one example, it has been shown that CD200/R−/− mice do not develop sepsis following influenza infection. CD200 is a negative regulator of innate immune responses resulting in down-regulating the innate immune response in general. Hence, certain methods of treatment may include the administration of antisense and/or RNAi agents targeted against a host RNA molecule encoding CD200 and/or the CD200 receptor (see, e.g., Hatherly et al., Eur J Immunol. 34:1688-94, 2004) in combination with the administration (concurrently or separately) of any one or more of the influenza-targeted antisense agents described herein. Also included are compositions that comprise an antisense or RNAi agent targeted against CD200 and/or the CD200 receptor (e.g., targeting its AUG start codon or a splice site) in combination with an antisense or RNAi agent targeted against influenza virus, as described herein. These methods and compositions can be used to treat stand-alone influenza virus infections, and/or secondary bacterial infections (e.g., Streptococcal pneumonia) associated with influenza virus infections.

Embodiments of the present invention also include combination therapies for the treatment of viral infections (e.g., influenza infections) accompanied by secondary bacterial infections. The majority of deaths in the 1918-1919 influenza pandemic likely resulted from secondary bacterial pneumonia caused by common upper respiratory-tract bacteria, such as Streptococcus pneumoniae, and recent evidence from the H1N1 pandemic of 2009 indicates secondary bacterial infections remain an important cause of death (see, e.g., Louie et al., Clin Infect Disease. 50:e59-62, 2010; Jain et al., N Engl J Med. 361:1935-44, 2009; Jamieson et al., Cell Host Microbe. 7:103-14, 2010). The standard of care for Streptococcal pneumonia includes antibiotics. Primary antibiotics include bactericidal beta-lactam agents such as penicillin and amoxicillin, second line agents include cephalosporins, and third line agents include chloramphenicol or clindamycin. Accordingly, embodiments of the present invention include methods and compositions related to the administration (concurrently or separately) of one or more bacteristatic or bactericidal antibiotics (e.g., penicillin, amoxicillin, cephalosporins, chloramphenicol, clindamycin) in combination with one or more influenza-targeted antisense or RNAi agents provided herein, mainly to treat or manage secondary bacterial infections associated with influenza virus infection.

As another example, the antisense oligonucleotides and RNAi agents of the present invention may be administered (concurrently or separately) in combination with other influenza virus-targeted therapies, such as oseltamivir phosphate (TAMIFLU®). In certain aspects, the combination of one or more antisense oligonucleotides (e.g., AVI-7100) and oseltamivir can achieve synergistic effects in the reduction of influenza viral titer and/or other symptoms of influenza virus infection (e.g., alveolitis, infiltrating immune cells), relative to the use of oseltamivir alone or antiviral antisense oligonucleotides alone. Also included are compositions that comprise oseltamivir in combination with an antiviral antisense oligonucleotide or RNAi agent targeted against influenza virus, as described herein. In specific embodiments, these compositions and methods can be used in the treatment of otherwise oseltamivir-resistant influenza virus infections.

Identification of an Infective Agent

The specific virus causing the infection can be determined by methods known in the art, e.g., serological or cultural methods.

Serological identification employs a viral sample or culture isolated from a biological specimen, e.g., saliva, stool, urine, cerebrospinal fluid, blood, etc., of the subject. Immunoassay for the detection of virus is generally carried out by methods routinely employed by those of skill in the art, e.g., ELISA or Western blot. In addition, monoclonal antibodies specific to particular viral strains or species are often commercially available.

Culture methods may be used to isolate and identify particular types of virus, by employing techniques including, but not limited to, comparing characteristics such as rates of growth and morphology under various culture conditions.

Another method for identifying the viral infective agent in an infected subject employs isolating RNA from a biological specimen followed by nucleic acid amplification using specific PCR primers that target suspected viral agents, e.g., seasonal H1N1 influenza, pandemic H1N1 S-OIV, H5N1 avian influenza or H3N2 swine influenza.

Formulations and Administration

In certain embodiments, the present invention provides formulations or compositions suitable for the therapeutic delivery of antisense oligomers, as described herein. Hence, in certain embodiments, the present invention provides pharmaceutically acceptable compositions that comprise a therapeutically-effective amount of one or more of the oligomers described herein, formulated together with one or more pharmaceutically acceptable carriers (additives) and/or diluents. While it is possible for an oligomer of the present invention to be administered alone, it is preferable to administer the compound as a pharmaceutical formulation (composition).

Methods for the delivery of nucleic acid molecules are described, for example, in Akhtar et al., 1992, Trends Cell Bio., 2:139; and Delivery Strategies for Antisense Oligonucleotide Therapeutics, ed. Akhtar; Sullivan et al., PCT WO 94/02595. These and other protocols can be utilized for the delivery of virtually any nucleic acid molecule, including the isolated oligomers of the present invention.

As detailed below, the pharmaceutical compositions of the present invention may be specially formulated for administration in solid or liquid form, including those adapted for the following: (1) oral administration, for example, drenches (aqueous or non-aqueous solutions or suspensions), tablets, e.g., those targeted for buccal, sublingual, and systemic absorption, boluses, powders, granules, pastes for application to the tongue; (2) parenteral administration, for example, by subcutaneous, intramuscular, intravenous or epidural injection as, for example, a sterile solution or suspension, or sustained-release formulation; (3) topical application, for example, as a cream, ointment, or a controlled-release patch or spray applied to the skin; (4) intravaginally or intrarectally, for example, as a pessary, cream or foam; (5) sublingually; (6) ocularly; (7) transdermally; or (8) nasally.

The phrase “pharmaceutically acceptable” is employed herein to refer to those compounds, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit/risk ratio.

The phrase “pharmaceutically-acceptable carrier” as used herein means a pharmaceutically-acceptable material, composition or vehicle, such as a liquid or solid filler, diluent, excipient, manufacturing aid (e.g., lubricant, talc magnesium, calcium or zinc stearate, or steric acid), or solvent encapsulating material, involved in carrying or transporting the subject compound from one organ, or portion of the body, to another organ, or portion of the body. Each carrier must be “acceptable” in the sense of being compatible with the other ingredients of the formulation and not injurious to the patient.

Some examples of materials that can serve as pharmaceutically-acceptable carriers include, without limitation: (1) sugars, such as lactose, glucose and sucrose; (2) starches, such as corn starch and potato starch; (3) cellulose, and its derivatives, such as sodium carboxymethyl cellulose, ethyl cellulose and cellulose acetate; (4) powdered tragacanth; (5) malt; (6) gelatin; (7) talc; (8) excipients, such as cocoa butter and suppository waxes; (9) oils, such as peanut oil, cottonseed oil, safflower oil, sesame oil, olive oil, corn oil and soybean oil; (10) glycols, such as propylene glycol; (11) polyols, such as glycerin, sorbitol, mannitol and polyethylene glycol; (12) esters, such as ethyl oleate and ethyl laurate; (13) agar; (14) buffering agents, such as magnesium hydroxide and aluminum hydroxide; (15) alginic acid; (16) pyrogen-free water; (17) isotonic saline; (18) Ringer's solution; (19) ethyl alcohol; (20) pH buffered solutions; (21) polyesters, polycarbonates and/or polyanhydrides; and (22) other non-toxic compatible substances employed in pharmaceutical formulations.

Additional non-limiting examples of agents suitable for formulation with the antisense oligomers of the instant invention include: PEG conjugated nucleic acids, phospholipid conjugated nucleic acids, nucleic acids containing lipophilic moieties, phosphorothioates, P-glycoprotein inhibitors (such as Pluronic P85) which can enhance entry of drugs into various tissues; biodegradable polymers, such as poly(DL-lactide-coglycolide) microspheres for sustained release delivery after implantation (Emerich, D F et al., Cell Transplant. 8:47-58, 1999) Alkermes, Inc. Cambridge, Mass.; and loaded nanoparticles, such as those made of polybutylcyanoacrylate, which can deliver drugs across the blood brain barrier and can alter neuronal uptake mechanisms (Prog Neuropsychopharmacol Biol Psychiatry, 23, 941-949, 1999).

The invention also features the use of the composition comprising surface-modified liposomes containing poly(ethylene glycol) lipids (PEG-modified, branched and unbranched or combinations thereof, or long-circulating liposomes or stealth liposomes). Oligomers of the invention can also comprise covalently attached PEG molecules of various molecular weights. These formulations offer a method for increasing the accumulation of drugs in target tissues. This class of drug carriers resists opsonization and elimination by the mononuclear phagocytic system (MPS or RES), thereby enabling longer blood circulation times and enhanced tissue exposure for the encapsulated drug (Lasic et al. Chem. Rev. 1995, 95, 2601-2627; Ishiwata et al., Chem. Pharm. Bull. 1995, 43, 1005-1011). Such liposomes have been shown to accumulate selectively in tumors, presumably by extravasation and capture in the neovascularized target tissues (Lasic et al., Science. 267:1275-1276, 1995; Oku et al., Biochim. Biophys. Acta. 1238:86-90, 1995). The long-circulating liposomes enhance the pharmacokinetics and pharmacodynamics of DNA and RNA, particularly compared to conventional cationic liposomes which are known to accumulate in tissues of the MPS (Liu et al., J. Biol. Chem. 42:24864-24870, 1995; Choi et al., International PCT Publication No. WO 96/10391; Ansell et al., International PCT Publication No. WO 96/10390; Holland et al., International PCT Publication No. WO 96/10392). Long-circulating liposomes are also likely to protect drugs from nuclease degradation to a greater extent compared to cationic liposomes, based on their ability to avoid accumulation in metabolically aggressive MPS tissues such as the liver and spleen.

In a further embodiment, the present invention includes oligomer compositions prepared for delivery as described in U.S. Pat. Nos. 6,692,911, 7,163,695 and 7,070,807. In this regard, in one embodiment, the present invention provides an oligomer of the present invention in a composition comprising copolymers of lysine and histidine (HK) as described in U.S. Pat. Nos. 7,163,695, 7,070,807, and 6,692,911 either alone or in combination with PEG (e.g., branched or unbranched PEG or a mixture of both), in combination with PEG and a targeting moiety or any of the foregoing in combination with a crosslinking agent. In certain embodiments, the present invention provides antisense oligomers in compositions comprising gluconic-acid-modified polyhistidine or gluconylated-polyhistidine/transferrin-polylysine. One skilled in the art will also recognize that amino acids with properties similar to His and Lys may be substituted within the composition.

Certain embodiments of the oligomers described herein may contain a basic functional group, such as amino or alkylamino, and are, thus, capable of forming pharmaceutically-acceptable salts with pharmaceutically-acceptable acids. The term “pharmaceutically-acceptable salts” in this respect, refers to the relatively non-toxic, inorganic and organic acid addition salts of compounds of the present invention. These salts can be prepared in situ in the administration vehicle or the dosage form manufacturing process, or by separately reacting a purified compound of the invention in its free base form with a suitable organic or inorganic acid, and isolating the salt thus formed during subsequent purification. Representative salts include the hydrobromide, hydrochloride, sulfate, bisulfate, phosphate, nitrate, acetate, valerate, oleate, palmitate, stearate, laurate, benzoate, lactate, phosphate, tosylate, citrate, maleate, fumarate, succinate, tartrate, napthylate, mesylate, glucoheptonate, lactobionate, and laurylsulphonate salts and the like. (See, e.g., Berge et al., J. Pharm. Sci. 66:1-19, 1977).

The pharmaceutically acceptable salts of the subject oligomers include the conventional nontoxic salts or quaternary ammonium salts of the compounds, e.g., from non-toxic organic or inorganic acids. For example, such conventional nontoxic salts include those derived from inorganic acids such as hydrochloride, hydrobromic, sulfuric, sulfamic, phosphoric, nitric, and the like; and the salts prepared from organic acids such as acetic, propionic, succinic, glycolic, stearic, lactic, malic, tartaric, citric, ascorbic, palmitic, maleic, hydroxymaleic, phenylacetic, glutamic, benzoic, salicyclic, sulfanilic, 2-acetoxybenzoic, fumaric, toluenesulfonic, methanesulfonic, ethane disulfonic, oxalic, isothionic, and the like.

In certain embodiments, the oligomers of the present invention may contain one or more acidic functional groups and, thus, are capable of forming pharmaceutically-acceptable salts with pharmaceutically-acceptable bases. The term “pharmaceutically-acceptable salts” in these instances refers to the relatively non-toxic, inorganic and organic base addition salts of compounds of the present invention. These salts can likewise be prepared in situ in the administration vehicle or the dosage form manufacturing process, or by separately reacting the purified compound in its free acid form with a suitable base, such as the hydroxide, carbonate or bicarbonate of a pharmaceutically-acceptable metal cation, with ammonia, or with a pharmaceutically-acceptable organic primary, secondary or tertiary amine. Representative alkali or alkaline earth salts include the lithium, sodium, potassium, calcium, magnesium, and aluminum salts and the like. Representative organic amines useful for the formation of base addition salts include ethylamine, diethylamine, ethylenediamine, ethanolamine, diethanolamine, piperazine and the like. (See, e.g., Berge et al., supra).

Wetting agents, emulsifiers and lubricants, such as sodium lauryl sulfate and magnesium stearate, as well as coloring agents, release agents, coating agents, sweetening, flavoring and perfuming agents, preservatives and antioxidants can also be present in the compositions.

Examples of pharmaceutically-acceptable antioxidants include: (1) water soluble antioxidants, such as ascorbic acid, cysteine hydrochloride, sodium bisulfate, sodium metabisulfite, sodium sulfite and the like; (2) oil-soluble antioxidants, such as ascorbyl palmitate, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), lecithin, propyl gallate, alpha-tocopherol, and the like; and (3) metal chelating agents, such as citric acid, ethylenediamine tetraacetic acid (EDTA), sorbitol, tartaric acid, phosphoric acid, and the like.

Formulations of the present invention include those suitable for oral, nasal, topical (including buccal and sublingual), rectal, vaginal and/or parenteral administration. The formulations may conveniently be presented in unit dosage form and may be prepared by any methods well known in the art of pharmacy. The amount of active ingredient that can be combined with a carrier material to produce a single dosage form will vary depending upon the host being treated, the particular mode of administration. The amount of active ingredient which can be combined with a carrier material to produce a single dosage form will generally be that amount of the compound which produces a therapeutic effect. Generally, out of one hundred percent, this amount will range from about 0.1 percent to about ninety-nine percent of active ingredient, preferably from about 5 percent to about 70 percent, most preferably from about 10 percent to about 30 percent.

In certain embodiments, a formulation of the present invention comprises an excipient selected from cyclodextrins, celluloses, liposomes, micelle forming agents, e.g., bile acids, and polymeric carriers, e.g., polyesters and polyanhydrides; and an oligomer of the present invention. In certain embodiments, an aforementioned formulation renders orally bioavailable an oligomer of the present invention.

Methods of preparing these formulations or compositions include the step of bringing into association an oligomer of the present invention with the carrier and, optionally, one or more accessory ingredients. In general, the formulations are prepared by uniformly and intimately bringing into association a compound of the present invention with liquid carriers, or finely divided solid carriers, or both, and then, if necessary, shaping the product.

Formulations of the invention suitable for oral administration may be in the form of capsules, cachets, pills, tablets, lozenges (using a flavored basis, usually sucrose and acacia or tragacanth), powders, granules, or as a solution or a suspension in an aqueous or non-aqueous liquid, or as an oil-in-water or water-in-oil liquid emulsion, or as an elixir or syrup, or as pastilles (using an inert base, such as gelatin and glycerin, or sucrose and acacia) and/or as mouth washes and the like, each containing a predetermined amount of a compound of the present invention as an active ingredient. An oligomer of the present invention may also be administered as a bolus, electuary or paste.

In solid dosage forms of the invention for oral administration (capsules, tablets, pills, dragees, powders, granules, trouches and the like), the active ingredient may be mixed with one or more pharmaceutically-acceptable carriers, such as sodium citrate or dicalcium phosphate, and/or any of the following: (1) fillers or extenders, such as starches, lactose, sucrose, glucose, mannitol, and/or silicic acid; (2) binders, such as, for example, carboxymethylcellulose, alginates, gelatin, polyvinyl pyrrolidone, sucrose and/or acacia; (3) humectants, such as glycerol; (4) disintegrating agents, such as agar-agar, calcium carbonate, potato or tapioca starch, alginic acid, certain silicates, and sodium carbonate; (5) solution retarding agents, such as paraffin; (6) absorption accelerators, such as quaternary ammonium compounds and surfactants, such as poloxamer and sodium lauryl sulfate; (7) wetting agents, such as, for example, cetyl alcohol, glycerol monostearate, and non-ionic surfactants; (8) absorbents, such as kaolin and bentonite clay; (9) lubricants, such as talc, calcium stearate, magnesium stearate, solid polyethylene glycols, sodium lauryl sulfate, zinc stearate, sodium stearate, stearic acid, and mixtures thereof; (10) coloring agents; and (11) controlled release agents such as crospovidone or ethyl cellulose. In the case of capsules, tablets and pills, the pharmaceutical compositions may also comprise buffering agents. Solid compositions of a similar type may also be employed as fillers in soft and hard-shelled gelatin capsules using such excipients as lactose or milk sugars, as well as high molecular weight polyethylene glycols and the like.

A tablet may be made by compression or molding, optionally with one or more accessory ingredients. Compressed tablets may be prepared using binder (e.g., gelatin or hydroxypropylmethyl cellulose), lubricant, inert diluent, preservative, disintegrant (for example, sodium starch glycolate or cross-linked sodium carboxymethyl cellulose), surface-active or dispersing agent. Molded tablets may be made by molding in a suitable machine a mixture of the powdered compound moistened with an inert liquid diluent.

The tablets, and other solid dosage forms of the pharmaceutical compositions of the present invention, such as dragees, capsules, pills and granules, may optionally be scored or prepared with coatings and shells, such as enteric coatings and other coatings well known in the pharmaceutical-formulating art. They may also be formulated so as to provide slow or controlled release of the active ingredient therein using, for example, hydroxypropylmethyl cellulose in varying proportions to provide the desired release profile, other polymer matrices, liposomes and/or microspheres. They may be formulated for rapid release, e.g., freeze-dried. They may be sterilized by, for example, filtration through a bacteria-retaining filter, or by incorporating sterilizing agents in the form of sterile solid compositions which can be dissolved in sterile water, or some other sterile injectable medium immediately before use. These compositions may also optionally contain opacifying agents and may be of a composition that they release the active ingredient(s) only, or preferentially, in a certain portion of the gastrointestinal tract, optionally, in a delayed manner. Examples of embedding compositions which can be used include polymeric substances and waxes. The active ingredient can also be in micro-encapsulated form, if appropriate, with one or more of the above-described excipients.

Liquid dosage forms for oral administration of the compounds of the invention include pharmaceutically acceptable emulsions, microemulsions, solutions, suspensions, syrups and elixirs. In addition to the active ingredient, the liquid dosage forms may contain inert diluents commonly used in the art, such as, for example, water or other solvents, solubilizing agents and emulsifiers, such as ethyl alcohol, isopropyl alcohol, ethyl carbonate, ethyl acetate, benzyl alcohol, benzyl benzoate, propylene glycol, 1,3-butylene glycol, oils (in particular, cottonseed, groundnut, corn, germ, olive, castor and sesame oils), glycerol, tetrahydrofuryl alcohol, polyethylene glycols and fatty acid esters of sorbitan, and mixtures thereof.

Besides inert diluents, the oral compositions can also include adjuvants such as wetting agents, emulsifying and suspending agents, sweetening, flavoring, coloring, perfuming and preservative agents.

Suspensions, in addition to the active compounds, may contain suspending agents as, for example, ethoxylated isostearyl alcohols, polyoxyethylene sorbitol and sorbitan esters, microcrystalline cellulose, aluminum metahydroxide, bentonite, agar-agar and tragacanth, and mixtures thereof.

Formulations for rectal or vaginal administration may be presented as a suppository, which may be prepared by mixing one or more compounds of the invention with one or more suitable nonirritating excipients or carriers comprising, for example, cocoa butter, polyethylene glycol, a suppository wax or a salicylate, and which is solid at room temperature, but liquid at body temperature and, therefore, will melt in the rectum or vaginal cavity and release the active compound.

Formulations or dosage forms for the topical or transdermal administration of an oligomer as provided herein include powders, sprays, ointments, pastes, creams, lotions, gels, solutions, patches and inhalants. The active oligomers may be mixed under sterile conditions with a pharmaceutically-acceptable carrier, and with any preservatives, buffers, or propellants which may be required. The ointments, pastes, creams and gels may contain, in addition to an active compound of this invention, excipients, such as animal and vegetable fats, oils, waxes, paraffins, starch, tragacanth, cellulose derivatives, polyethylene glycols, silicones, bentonites, silicic acid, talc and zinc oxide, or mixtures thereof.

Powders and sprays can contain, in addition to an oligomer of the present invention, excipients such as lactose, talc, silicic acid, aluminum hydroxide, calcium silicates and polyamide powder, or mixtures of these substances. Sprays can additionally contain customary propellants, such as chlorofluorohydrocarbons and volatile unsubstituted hydrocarbons, such as butane and propane.

Transdermal patches have the added advantage of providing controlled delivery of an oligomer of the present invention to the body. Such dosage forms can be made by dissolving or dispersing the oligomer in the proper medium. Absorption enhancers can also be used to increase the flux of the agent across the skin. The rate of such flux can be controlled by either providing a rate controlling membrane or dispersing the agent in a polymer matrix or gel, among other methods known in the art.

Pharmaceutical compositions suitable for parenteral administration may comprise one or more oligomers of the invention in combination with one or more pharmaceutically-acceptable sterile isotonic aqueous or nonaqueous solutions, dispersions, suspensions or emulsions, or sterile powders which may be reconstituted into sterile injectable solutions or dispersions just prior to use, which may contain sugars, alcohols, antioxidants, buffers, bacteriostats, solutes which render the formulation isotonic with the blood of the intended recipient or suspending or thickening agents. Examples of suitable aqueous and nonaqueous carriers which may be employed in the pharmaceutical compositions of the invention include water, ethanol, polyols (such as glycerol, propylene glycol, polyethylene glycol, and the like), and suitable mixtures thereof, vegetable oils, such as olive oil, and injectable organic esters, such as ethyl oleate. Proper fluidity can be maintained, for example, by the use of coating materials, such as lecithin, by the maintenance of the required particle size in the case of dispersions, and by the use of surfactants.

These compositions may also contain adjuvants such as preservatives, wetting agents, emulsifying agents and dispersing agents. Prevention of the action of microorganisms upon the subject oligomers may be ensured by the inclusion of various antibacterial and antifungal agents, for example, paraben, chlorobutanol, phenol sorbic acid, and the like. It may also be desirable to include isotonic agents, such as sugars, sodium chloride, and the like into the compositions. In addition, prolonged absorption of the injectable pharmaceutical form may be brought about by the inclusion of agents which delay absorption such as aluminum monostearate and gelatin.

In some cases, in order to prolong the effect of a drug, it is desirable to slow the absorption of the drug from subcutaneous or intramuscular injection. This may be accomplished by the use of a liquid suspension of crystalline or amorphous material having poor water solubility, among other methods known in the art. The rate of absorption of the drug then depends upon its rate of dissolution which, in turn, may depend upon crystal size and crystalline form. Alternatively, delayed absorption of a parenterally-administered drug form is accomplished by dissolving or suspending the drug in an oil vehicle.

Injectable depot forms may be made by forming microencapsule matrices of the subject oligomers in biodegradable polymers such as polylactide-polyglycolide. Depending on the ratio of oligomer to polymer, and the nature of the particular polymer employed, the rate of oligomer release can be controlled. Examples of other biodegradable polymers include poly(orthoesters) and poly(anhydrides). Depot injectable formulations may also prepared by entrapping the drug in liposomes or microemulsions that are compatible with body tissues.

When the oligomers of the present invention are administered as pharmaceuticals, to humans and animals, they can be given per se or as a pharmaceutical composition containing, for example, 0.1 to 99% (more preferably, 10 to 30%) of active ingredient in combination with a pharmaceutically acceptable carrier.

As noted above, the formulations or preparations of the present invention may be given orally, parenterally, topically, or rectally. They are typically given in forms suitable for each administration route. For example, they are administered in tablets or capsule form, by injection, inhalation, eye lotion, ointment, suppository, etc. administration by injection, infusion or inhalation; topical by lotion or ointment; and rectal by suppositories.

The phrases “parenteral administration” and “administered parenterally” as used herein means modes of administration other than enteral and topical administration, usually by injection, and includes, without limitation, intravenous, intramuscular, intraarterial, intrathecal, intracapsular, intraorbital, intracardiac, intradermal, intraperitoneal, transtracheal, subcutaneous, subcuticular, intraarticulare, subcapsular, subarachnoid, intraspinal and intrasternal injection and infusion.

The phrases “systemic administration,” “administered systemically,” “peripheral administration” and “administered peripherally” as used herein mean the administration of a compound, drug or other material other than directly into the central nervous system, such that it enters the patient's system and, thus, is subject to metabolism and other like processes, for example, subcutaneous administration.

Regardless of the route of administration selected, the oligomers of the present invention, which may be used in a suitable hydrated form, and/or the pharmaceutical compositions of the present invention, may be formulated into pharmaceutically-acceptable dosage forms by conventional methods known to those of skill in the art. Actual dosage levels of the active ingredients in the pharmaceutical compositions of this invention may be varied so as to obtain an amount of the active ingredient which is effective to achieve the desired therapeutic response for a particular patient, composition, and mode of administration, without being unacceptably toxic to the patient.

The selected dosage level will depend upon a variety of factors including the activity of the particular oligomer of the present invention employed, or the ester, salt or amide thereof, the route of administration, the time of administration, the rate of excretion or metabolism of the particular oligomer being employed, the rate and extent of absorption, the duration of the treatment, other drugs, compounds and/or materials used in combination with the particular oligomer employed, the age, sex, weight, condition, general health and prior medical history of the patient being treated, and like factors well known in the medical arts.

A physician or veterinarian having ordinary skill in the art can readily determine and prescribe the effective amount of the pharmaceutical composition required. For example, the physician or veterinarian could start doses of the compounds of the invention employed in the pharmaceutical composition at levels lower than that required in order to achieve the desired therapeutic effect and gradually increase the dosage until the desired effect is achieved. In general, a suitable daily dose of a compound of the invention will be that amount of the compound which is the lowest dose effective to produce a therapeutic effect. Such an effective dose will generally depend upon the factors described above. Generally, oral, intravenous, intracerebroventricular and subcutaneous doses of the compounds of this invention for a patient, when used for the indicated effects, will range from about 0.0001 to about 100 mg per kilogram of body weight per day.

If desired, the effective daily dose of the active compound may be administered as two, three, four, five, six or more sub-doses administered separately at appropriate intervals throughout the day, optionally, in unit dosage forms. In certain situations, dosing is one administration per day. In certain embodiments, dosing is one or more administration per every 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 days, or every 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 weeks, or every 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 months, as needed, to reduce influenza virus replication.

Nucleic acid molecules can be administered to cells by a variety of methods known to those familiar to the art, including, but not restricted to, encapsulation in liposomes, by iontophoresis, or by incorporation into other vehicles, such as hydrogels, cyclodextrins, biodegradable nanocapsules, and bioadhesive microspheres, as described herein and known in the art. In certain embodiments, microemulsification technology may be utilized to improve bioavailability of lipophilic (water insoluble) pharmaceutical agents. Examples include Trimetrine (Dordunoo, S. K., et al., Drug Development and Industrial Pharmacy, 17:1685-1713, 1991) and REV 5901 (Sheen, P. C., et al., J Pharm Sci. 80:712-714, 1991). Among other benefits, microemulsification provides enhanced bioavailability by preferentially directing absorption to the lymphatic system instead of the circulatory system, which thereby bypasses the liver, and prevents destruction of the compounds in the hepatobiliary circulation.

In one aspect of invention, the formulations contain micelles formed from an oligomer as provided herein and at least one amphiphilic carrier, in which the micelles have an average diameter of less than about 100 nm. More preferred embodiments provide micelles having an average diameter less than about 50 nm, and even more preferred embodiments provide micelles having an average diameter less than about 30 nm, or even less than about 20 nm.

While all suitable amphiphilic carriers are contemplated, the presently preferred carriers are generally those that have Generally-Recognized-as-Safe (GRAS) status, and that can both solubilize the compound of the present invention and microemulsify it at a later stage when the solution comes into a contact with a complex water phase (such as one found in human gastro-intestinal tract). Usually, amphiphilic ingredients that satisfy these requirements have HLB (hydrophilic to lipophilic balance) values of 2-20, and their structures contain straight chain aliphatic radicals in the range of C-6 to C-20. Examples are polyethylene-glycolized fatty glycerides and polyethylene glycols.

Examples of amphiphilic carriers include saturated and monounsaturated polyethyleneglycolyzed fatty acid glycerides, such as those obtained from fully or partially hydrogenated various vegetable oils. Such oils may advantageously consist of tri-, di-, and mono-fatty acid glycerides and di- and mono-polyethyleneglycol esters of the corresponding fatty acids, with a particularly preferred fatty acid composition including capric acid 4-10, capric acid 3-9, lauric acid 40-50, myristic acid 14-24, palmitic acid 4-14 and stearic acid 5-15%. Another useful class of amphiphilic carriers includes partially esterified sorbitan and/or sorbitol, with saturated or mono-unsaturated fatty acids (SPAN-series) or corresponding ethoxylated analogs (TWEEN-series).

Commercially available amphiphilic carriers may be particularly useful, including Gelucire-series, Labrafil, Labrasol, or Lauroglycol (all manufactured and distributed by Gattefosse Corporation, Saint Priest, France), PEG-mono-oleate, PEG-di-oleate, PEG-mono-laurate and di-laurate, Lecithin, Polysorbate 80, etc (produced and distributed by a number of companies in USA and worldwide).

In certain embodiments, the delivery may occur by use of liposomes, nanocapsules, microparticles, microspheres, lipid particles, vesicles, and the like, for the introduction of the compositions of the present invention into suitable host cells. In particular, the compositions of the present invention may be formulated for delivery either encapsulated in a lipid particle, a liposome, a vesicle, a nanosphere, a nanoparticle or the like. The formulation and use of such delivery vehicles can be carried out using known and conventional techniques.

Hydrophilic polymers suitable for use in the present invention are those which are readily water-soluble, can be covalently attached to a vesicle-forming lipid, and which are tolerated in vivo without toxic effects (i.e., are biocompatible). Suitable polymers include polyethylene glycol (PEG), polylactic (also termed polylactide), polyglycolic acid (also termed polyglycolide), a polylactic-polyglycolic acid copolymer, and polyvinyl alcohol. In certain embodiments, polymers have a molecular weight of from about 100 or 120 daltons up to about 5,000 or 10,000 daltons, or from about 300 daltons to about 5,000 daltons. In other embodiments, the polymer is polyethyleneglycol having a molecular weight of from about 100 to about 5,000 daltons, or having a molecular weight of from about 300 to about 5,000 daltons. In certain embodiments, the polymer is polyethyleneglycol of 750 daltons (PEG(750)). Polymers may also be defined by the number of monomers therein; a preferred embodiment of the present invention utilizes polymers of at least about three monomers, such PEG polymers consisting of three monomers (approximately 150 daltons).

Other hydrophilic polymers which may be suitable for use in the present invention include polyvinylpyrrolidone, polymethoxazoline, polyethyloxazoline, polyhydroxypropyl methacrylamide, polymethacrylamide, polydimethylacrylamide, and derivatized celluloses such as hydroxymethylcellulose or hydroxyethylcellulose.

In certain embodiments, a formulation of the present invention comprises a biocompatible polymer selected from the group consisting of polyamides, polycarbonates, polyalkylenes, polymers of acrylic and methacrylic esters, polyvinyl polymers, polyglycolides, polysiloxanes, polyurethanes and co-polymers thereof, celluloses, polypropylene, polyethylenes, polystyrene, polymers of lactic acid and glycolic acid, polyanhydrides, poly(ortho)esters, poly(butic acid), poly(valeric acid), poly(lactide-co-caprolactone), polysaccharides, proteins, polyhyaluronic acids, polycyanoacrylates, and blends, mixtures, or copolymers thereof.

Cyclodextrins are cyclic oligosaccharides, consisting of 6, 7 or 8 glucose units, designated by the Greek letter α, β, or γ, respectively. The glucose units are linked by α-1,4-glucosidic bonds. As a consequence of the chair conformation of the sugar units, all secondary hydroxyl groups (at C-2, C-3) are located on one side of the ring, while all the primary hydroxyl groups at C-6 are situated on the other side. As a result, the external faces are hydrophilic, making the cyclodextrins water-soluble. In contrast, the cavities of the cyclodextrins are hydrophobic, since they are lined by the hydrogen of atoms C-3 and C-5, and by ether-like oxygens. These matrices allow complexation with a variety of relatively hydrophobic compounds, including, for instance, steroid compounds such as 17α-estradiol. The complexation takes place by Van der Waals interactions and by hydrogen bond formation. For a general review of the chemistry of cyclodextrins, see, Wenz, Agnew, Chem. Int. Ed. Engl., 33:803-822, 1994.

The physico-chemical properties of the cyclodextrin derivatives depend strongly on the kind and the degree of substitution. For example, their solubility in water ranges from insoluble (e.g., triacetyl-beta-cyclodextrin) to 147% soluble (w/v) (G-2-beta-cyclodextrin). In addition, they are soluble in many organic solvents. The properties of the cyclodextrins enable the control over solubility of various formulation components by increasing or decreasing their solubility.

Numerous cyclodextrins and methods for their preparation have been described. For example, Parmeter (I) et al. (U.S. Pat. No. 3,453,259) and Gramera et al. (U.S. Pat. No. 3,459,731) described electroneutral cyclodextrins. Other derivatives include cyclodextrins with cationic properties [Parmeter (II), U.S. Pat. No. 3,453,257], insoluble crosslinked cyclodextrins (Solms, U.S. Pat. No. 3,420,788), and cyclodextrins with anionic properties [Parmeter (III), U.S. Pat. No. 3,426,011]. Among the cyclodextrin derivatives with anionic properties, carboxylic acids, phosphorous acids, phosphinous acids, phosphonic acids, phosphoric acids, thiophosphonic acids, thiosulphinic acids, and sulfonic acids have been appended to the parent cyclodextrin [see, Parmeter (III), supra]. Furthermore, sulfoalkyl ether cyclodextrin derivatives have been described by Stella et al. (U.S. Pat. No. 5,134,127).

Liposomes consist of at least one lipid bilayer membrane enclosing an aqueous internal compartment. Liposomes may be characterized by membrane type and by size. Small unilamellar vesicles (SUVs) have a single membrane and typically range between 0.02 and 0.05 μm in diameter; large unilamellar vesicles (LUVS) are typically larger than 0.05 nm. Oligolamellar large vesicles and multilamellar vesicles have multiple, usually concentric, membrane layers and are typically larger than 0.1 nm. Liposomes with several nonconcentric membranes, i.e., several smaller vesicles contained within a larger vesicle, are termed multivesicular vesicles.

One aspect of the present invention relates to formulations comprising liposomes containing an oligomer of the present invention, where the liposome membrane is formulated to provide a liposome with increased carrying capacity. Alternatively or in addition, the compound of the present invention may be contained within, or adsorbed onto, the liposome bilayer of the liposome. An oligomer of the present invention may be aggregated with a lipid surfactant and carried within the liposome's internal space; in these cases, the liposome membrane is formulated to resist the disruptive effects of the active agent-surfactant aggregate.

According to one embodiment of the present invention, the lipid bilayer of a liposome contains lipids derivatized with polyethylene glycol (PEG), such that the PEG chains extend from the inner surface of the lipid bilayer into the interior space encapsulated by the liposome, and extend from the exterior of the lipid bilayer into the surrounding environment.

Active agents contained within liposomes of the present invention are in solubilized form. Aggregates of surfactant and active agent (such as emulsions or micelles containing the active agent of interest) may be entrapped within the interior space of liposomes according to the present invention. A surfactant acts to disperse and solubilize the active agent, and may be selected from any suitable aliphatic, cycloaliphatic or aromatic surfactant, including but not limited to biocompatible lysophosphatidylcholines (LPCs) of varying chain lengths (for example, from about C14 to about C20). Polymer-derivatized lipids such as PEG-lipids may also be utilized for micelle formation as they will act to inhibit micelle/membrane fusion, and as the addition of a polymer to surfactant molecules decreases the CMC of the surfactant and aids in micelle formation. Preferred are surfactants with CMCs in the micromolar range; higher CMC surfactants may be utilized to prepare micelles entrapped within liposomes of the present invention.

Liposomes according to the present invention may be prepared by any of a variety of techniques that are known in the art. See, e.g., U.S. Pat. No. 4,235,871; Published PCT applications WO 96/14057; New RRC, Liposomes: A Practical Approach, IRL Press, Oxford (1990), pages 33-104; Lasic D D, Liposomes from physics to applications, Elsevier Science Publishers BV, Amsterdam, 1993. For example, liposomes of the present invention may be prepared by diffusing a lipid derivatized with a hydrophilic polymer into preformed liposomes, such as by exposing preformed liposomes to micelles composed of lipid-grafted polymers, at lipid concentrations corresponding to the final mole percent of derivatized lipid which is desired in the liposome. Liposomes containing a hydrophilic polymer can also be formed by homogenization, lipid-field hydration, or extrusion techniques, as are known in the art.

In another exemplary formulation procedure, the active agent is first dispersed by sonication in a lysophosphatidylcholine or other low CMC surfactant (including polymer grafted lipids) that readily solubilizes hydrophobic molecules. The resulting micellar suspension of active agent is then used to rehydrate a dried lipid sample that contains a suitable mole percent of polymer-grafted lipid, or cholesterol. The lipid and active agent suspension is then formed into liposomes using extrusion techniques as are known in the art, and the resulting liposomes separated from the unencapsulated solution by standard column separation.

In one aspect of the present invention, the liposomes are prepared to have substantially homogeneous sizes in a selected size range. One effective sizing method involves extruding an aqueous suspension of the liposomes through a series of polycarbonate membranes having a selected uniform pore size; the pore size of the membrane will correspond roughly with the largest sizes of liposomes produced by extrusion through that membrane. See e.g., U.S. Pat. No. 4,737,323. In certain embodiments, reagents such as DharmaFECT® and Lipofectamine® may be utilized to introduce polynucleotides or proteins into cells.

The release characteristics of a formulation of the present invention depend on the encapsulating material, the concentration of encapsulated drug, and the presence of release modifiers. For example, release can be manipulated to be pH dependent, for example, using a pH sensitive coating that releases only at a low pH, as in the stomach, or a higher pH, as in the intestine. An enteric coating can be used to prevent release from occurring until after passage through the stomach. Multiple coatings or mixtures of cyanamide encapsulated in different materials can be used to obtain an initial release in the stomach, followed by later release in the intestine. Release can also be manipulated by inclusion of salts or pore forming agents, which can increase water uptake or release of drug by diffusion from the capsule. Excipients which modify the solubility of the drug can also be used to control the release rate. Agents which enhance degradation of the matrix or release from the matrix can also be incorporated. They can be added to the drug, added as a separate phase (i.e., as particulates), or can be co-dissolved in the polymer phase depending on the compound. In most cases the amount should be between 0.1 and thirty percent (w/w polymer). Types of degradation enhancers include inorganic salts such as ammonium sulfate and ammonium chloride, organic acids such as citric acid, benzoic acid, and ascorbic acid, inorganic bases such as sodium carbonate, potassium carbonate, calcium carbonate, zinc carbonate, and zinc hydroxide, and organic bases such as protamine sulfate, spermine, choline, ethanolamine, diethanolamine, and triethanolamine and surfactants such as Tween® and Pluronic®. Pore forming agents which add microstructure to the matrices (i.e., water soluble compounds such as inorganic salts and sugars) are added as particulates. The range is typically between one and thirty percent (w/w polymer).

Uptake can also be manipulated by altering residence time of the particles in the gut. This can be achieved, for example, by coating the particle with, or selecting as the encapsulating material, a mucosal adhesive polymer. Examples include most polymers with free carboxyl groups, such as chitosan, celluloses, and especially polyacrylates (as used herein, polyacrylates refers to polymers including acrylate groups and modified acrylate groups such as cyanoacrylates and methacrylates).

An oligomer may be formulated to be contained within, or, adapted to release by a surgical or medical device or implant. In certain aspects, an implant may be coated or otherwise treated with an oligomer. For example, hydrogels, or other polymers, such as biocompatible and/or biodegradable polymers, may be used to coat an implant with the compositions of the present invention (i.e., the composition may be adapted for use with a medical device by using a hydrogel or other polymer). Polymers and copolymers for coating medical devices with an agent are well-known in the art. Examples of implants include, but are not limited to, stents, drug-eluting stents, sutures, prosthesis, vascular catheters, dialysis catheters, vascular grafts, prosthetic heart valves, cardiac pacemakers, implantable cardioverter defibrillators, IV needles, devices for bone setting and formation, such as pins, screws, plates, and other devices, and artificial tissue matrices for wound healing.

In addition to the methods provided herein, the oligomers for use according to the invention may be formulated for administration in any convenient way for use in human or veterinary medicine, by analogy with other pharmaceuticals. The antisense oligomers and their corresponding formulations may be administered alone or in combination with other therapeutic strategies in the treatment of influenza virus infection (e.g., Oseltamivir, which is marketed under the trade name TAMIFLU®).

In accordance with the invention, routes of antisense oligomer delivery include, but are not limited to, various systemic routes, including oral and parenteral routes, e.g., intravenous, subcutaneous, intraperitoneal, and intramuscular, as well as inhalation, transdermal, pulmonary and topical delivery. The appropriate route may be determined by one of skill in the art, as appropriate to the condition of the subject under treatment. For example, an appropriate route for delivery of an antisense oligomer in the treatment of a viral infection of the skin is topical delivery, while delivery of a antisense oligomer for the treatment of a viral respiratory infection (e.g., influenza A) is by inhalation, intranasal or pulmonary delivery. The oligomer may also be delivered directly to the site of viral infection, or to the bloodstream.

The antisense oligomer may be administered in any convenient vehicle which is physiologically acceptable. Such a composition may include any of a variety of standard pharmaceutically acceptable carriers employed by those of ordinary skill in the art. Examples include, but are not limited to, saline, phosphate buffered saline (PBS), water, aqueous ethanol, emulsions, such as oil/water emulsions or triglyceride emulsions, tablets and capsules. The choice of suitable physiologically acceptable carrier will vary dependent upon the chosen mode of administration.

In some instances, as noted above, liposomes may be employed to facilitate uptake of the antisense oligonucleotide into cells. (See, e.g., Williams, S. A., Leukemia. 10(12):1980-1989, 1996; Lappalainen et al., Antiviral Res. 23:119, 1994; Uhlmann et al., Antisense Oligonucleotides: A New Therapeutic Principle, Chemical Reviews, Volume 90, No. 4, pages 544-584, 1990; Gregoriadis, G., Chapter 14, Liposomes, Drug Carriers in Biology and Medicine, pp. 287-341, Academic Press, 1979). Hydrogels may also be used as vehicles for antisense oligomer administration, for example, as described in WO 93/01286 or PCT Application No. US1992/005305. Alternatively, the oligonucleotides may be administered in microspheres or microparticles. (See, e.g., Wu, G. Y. and Wu, C. H. J. Biol. Chem. 262:4429-4432, 1987). Alternatively, the use of gas-filled microbubbles complexed with the antisense oligomers can enhance delivery to target tissues, as described in U.S. Pat. No. 6,245,747.

Sustained release compositions may also be used. These may include semipermeable polymeric matrices in the form of shaped articles such as films or microcapsules.

In one aspect of the method, the subject is a human subject, e.g., a patient diagnosed as having a localized or systemic viral infection. The condition of a patient may also dictate prophylactic administration of an antisense oligomer of the invention, e.g., in the case of a patient who (1) is immunocompromised; (2) is a burn victim; (3) has an indwelling catheter; or (4) is about to undergo or has recently undergone surgery. In one preferred embodiment, the oligomer is a phosphorodiamidate morpholino oligomer, contained in a pharmaceutically acceptable carrier, and is delivered orally. In another preferred embodiment, the oligomer is a phosphorodiamidate morpholino oligomer, contained in a pharmaceutically acceptable carrier, and is delivered intravenously (i.v.).

The antisense compounds may be administered in an amount and manner effective to result in a peak blood concentration of at least 200-400 nM antisense oligomer. Typically, one or more doses of antisense oligomer are administered, generally at regular intervals, for a period of about one to two weeks. Preferred doses for oral administration are from about 1-100 mg oligomer per 70 kg. In some cases, doses of greater than 100 mg oligomer/patient may be necessary. For i.v. administration, preferred doses are from about 1 mg to 500 mg oligomer per 70 kg. The antisense oligomer may be administered at regular intervals for a short time period, e.g., daily for two weeks or less. However, in some cases the oligomer is administered intermittently over a longer period of time. Administration may be followed by, or concurrent with, administration of an antibiotic or other therapeutic treatment. The treatment regimen may be adjusted (dose, frequency, route, etc.) as indicated, based on the results of immunoassays, other biochemical tests and physiological examination of the subject under treatment.

Monitoring of Treatment

An effective in vivo treatment regimen using the antisense oligonucleotides of the invention may vary according to the duration, dose, frequency and route of administration, as well as the condition of the subject under treatment (i.e., prophylactic administration versus administration in response to localized or systemic infection). Accordingly, such in vivo therapy will often require monitoring by tests appropriate to the particular type of viral infection under treatment, and corresponding adjustments in the dose or treatment regimen, in order to achieve an optimal therapeutic outcome. Treatment may be monitored, e.g., by general indicators of infection, such as complete blood count (CBC), nucleic acid detection methods, immunodiagnostic tests, viral culture, or detection of heteroduplex.

The efficacy of an in vivo administered antisense oligomer of the invention in inhibiting or eliminating the growth of one or more types of RNA virus may be determined from biological samples (tissue, blood, urine, etc.) taken from a subject prior to, during and subsequent to administration of the antisense oligomer. Assays of such samples include (1) monitoring the presence or absence of heteroduplex formation with target and non-target sequences, using procedures known to those skilled in the art, e.g., an electrophoretic gel mobility assay; (2) monitoring the amount of viral protein production, as determined by standard techniques such as ELISA or Western blotting, or (3) measuring the effect on viral titer, e.g., by the method of Spearman-Karber. (See, for example, Pari, G. S. et al., Antimicrob. Agents and Chemotherapy. 39(5):1157-1161, 1995; Anderson, K. P. et al., Antimicrob. Agents and Chemotherapy. 40:2004-2011, 1996; Cottral, G. E. (ed) in: Manual of Standard Methods for Veterinary Microbiology, pp. 60-93, 1978).

REFERENCES

-   Abes, R., H. M. Moulton, et al. (2008). “Delivery of steric block     morpholino oligomers by (R-X-R)4 peptides: structure-activity     studies.” Nucleic Acids Res. -   Cox, N. J. and K. Subbarao (1999). “Influenza.” Lancet 354(9186):     1277-82. -   Cox, N. J. and K. Subbarao (2000). “Global epidemiology of     influenza: past and present.” Annu Rev Med 51: 407-21. -   Egholm, M., O. Buchardt, et al. (1993). “PNA hybridizes to     complementary oligonucleotides obeying the Watson-Crick     hydrogen-bonding rules.” Nature 365(6446): 566-8. -   Jearawiriyapaisarn, N., H. M. Moulton, et al. (2008). “Sustained     Dystrophin Expression Induced by Peptide-conjugated Morpholino     Oligomers in the Muscles of mdx Mice.” Mol. Ther. -   Marshall, N. B., S. K. Oda, et al. (2007). “Arginine-rich     cell-penetrating peptides facilitate delivery of antisense oligomers     into murine leukocytes and alter pre-mRNA splicing.” Journal of     Immunological Methods 325(1-2): 114-126. -   Moulton, H. M., M. H. Nelson, et al. (2004). “Cellular uptake of     antisense morpholino oligomers conjugated to arginine-rich     peptides.” Bioconjug Chem 15(2): 290-9. -   Munster, V. J., E. de Wit, et al. (2009). “Pathogenesis and     Transmission of Swine-Origin 2009 A(H1N1) Influenza Virus in     Ferrets.” Science. -   Stein, C. A., J. B. Hansen, et al. (2010). “Efficient gene silencing     by delivery of locked nucleic acid antisense oligonucleotides,     unassisted by transfection reagents.” Nucleic Acids Res 38(1): e3. -   Strauss, J. H. and E. G. Strauss (2002). Viruses and Human Disease.     San Diego, Academic Press. -   Summerton, J. and D. Weller (1997). “Morpholino antisense oligomers:     design, preparation, and properties.” Antisense Nucleic Acid Drug     Dev 7(3): 187-95. -   Wu, B., H. M. Moulton, et al. (2008). “Effective rescue of     dystrophin improves cardiac function in dystrophin-deficient mice by     a modified morpholino oligomer.” Proc Natl Acad Sci USA 105(39):     14814-9.

All publications and patent applications cited in this specification are herein incorporated by reference as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference.

Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it will be readily apparent to one of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto without departing from the spirit or scope of the appended claims. The following examples are provided by way of illustration only and not by way of limitation. Those of skill in the art will readily recognize a variety of noncritical parameters that could be changed or modified to yield essentially similar results.

EXAMPLES A. Materials and Methods

All peptides were custom synthesized by Global Peptide Services (Ft. Collins, Colo.) or at AVI BioPharma (Corvallis, Oreg.) and purified to >90% purity (see Example 2 below). PMOs were synthesized at AVI BioPharma in accordance with known methods, as described, for example, in ((Summerton and Weller 1997) and U.S. Pat. No. 5,185,444 and further described in PCT application No. US08/012804. Exemplary structures of the PMO are as shown in FIGS. 1A-C. 2′-OMe oligomers were synthesized by Integrated DNA Technologies Inc., Skokie, Ill. LNA oligomers were produced by Biosynthesis, Inc., Lewisville, Tex.

Some of the PMO oligomers were conjugated at the 3′ end with an arginine-rich peptide ((RAhxRRBR)₂AhxB or (RAhxR)₄AhxB; SEQ ID NOs: 124 and 118, respectively) to form peptide-conjugated PMOs (PPMOs) to enhance cellular uptake as described (U.S. Pat. No. 7,468,418, PCT application No. US08/008168 and (Marshall, Oda et al. 2007; Abes, Moulton et al. 2008)).

A synthetic pathway that can be used to make morpholino subunits containing a (1-piperazino) phosphinylideneoxy linkage is described in PCT application No. US07/011435 and further experimental detail for a representative synthesis is provided below. Reaction of piperazine and trityl chloride gave trityl piperazine, which was isolated as the succinate salt. Reaction with ethyl trifluoroacetate in the presence of a weak base (such as diisopropylethylamine or DIEA) provided 1-trifluoroacetyl-4-trityl piperazine, which was immediately reacted with HCl to provide the salt in good yield. Introduction of the dichlorophosphoryl moiety was performed with phosphorus oxychloride in toluene.

The acid chloride is reacted with morpholino subunits (moN), which may be prepared as described in U.S. Pat. No. 5,185,444 or in Summerton and Weller, 1997 (cited above) and further described in PCT application No. US08/012804, to provide the activated subunits. Suitable protecting groups are used for the nucleoside bases, where necessary; for example, benzoyl for adenine and cytosine, phenylacetyl for guanine, and pivaloylmethyl for inosine. The subunits containing the (1-piperazino) phosphinylideneoxy linkage can be incorporated into the existing PMO synthesis protocol, as described, for example in Summerton and Weller (1997), without modification.

Example 1 Inhibition of Influenza a Virus in a Murine Model System

A murine model of influenza A virus infection was used to determine the in vivo efficacy of representative antisense oligomers of the infection. Influenza A subtype H₂N₃ (Port Chalmers/1/73) was used to infect Balb/c female mice via intranasal administration of approximately 4×10⁴ plaque-forming units in a 50 microliter volume. The studies used 12 mice per group with six removed on day two for determination of viral titer and six removed on day six for determination of viral titer. Secondary endpoints included prevention of weight loss and survival.

Three test antisense oligomer compounds, PB1-AUG+15, M1/M2-AUG and NP-v3′ (SEQ ID NOs:12, 13 and 30-33) as listed in Table 1 and below in Table 6 were evaluated as both peptide conjugated (PPMO) and positive charge linkage chemistry (PMOplus™). The PPMOs were synthesized using the CP06062 peptide (SEQ ID NO:124) conjugated to the 3′ terminus of the PMO. Each test agent was evaluated at three dose levels (10, 30 and 100 micrograms) to establish dose-dependent relationships. Dosing was via the intranasal route beginning 4 hours prior to infection on Day 0 and then daily through Day 4 for a total of 5 doses. The primary endpoint of the study was viral titer reduction in the lung measured as plaque-forming units per gram of lung tissue.

TABLE 6 Antisense Oligomers Used in the H3N2 Murine Model Name Sequence 3′End SEQ ID NO NP-v3′ AGC AAA AGC AGI GTA GAT AAT C CP06062 30 NP-v3′plus AGC AAA AGC AGI G+TA GA+T AA+T C H 31 M1/M2-AUG CGG TTA GAA GAC TCA TCT TT CP06062 12 M1/M2-AUGplus CGG T+TA GAA GAC +TCA TC+T TT H 13 (AVI-7100) PB1-AUG + 15 CGG ATT GAC ATC CAT TCA AAT G CP06062 32 PB1-AUG + 15plus CGG AT+T GAC A+TC CAT +TCA AAT G H 33

FIG. 6 shows the effect on viral titer at Day 6 post-infection. Each viral titer is the average of the six PPMO and six PMOplus™ treated animals. The M1/M2-AUG targeted compounds (SEQ ID NOs: 12 and 13) showed substantially greater activity compared to the other compounds tested. The viral titer from the negative control Dengue treatment shown in FIG. 6 was obtained using an irrelevant PPMO and PMOplus™ sequence that targets the Dengue virus.

Example 2 Inhibition of Influenza a Virus in a Ferret Model System

One observation in support of the present invention was the demonstration of antiviral efficacy of the compounds of the invention in the domestic ferret (Mustela putorius furo) animal model system using the novel H1N12009 (S-OIV) virus. Advantages of the ferret model include the ability to use natural human isolate of influenza virus, as opposed to mouse-adapted strains, and the development of most clinical signs observed in humans such as fever and nasal discharge (Munster, de Wit et al. 2009).

Six ferrets were infected with a Tamiflu-resistant H1N1 strain from 2009 obtained from the Centers for Disease Control (pandemic swine flu). The route of viral infection was intranasal (4×10⁴ plaque-forming units) on Day 1 and dosing was either by intraperitoneal (ip) injection for the PMOplus™ compounds or intranasal (in) for the PPMO compounds. The Dengue-targeted negative control PMOplus™ (30 mg/kg ip dose) and PPMO (1.5 mg/kg in dose) compounds were administered as described above in Example 1. The dosing for PMOplus™ compounds was 10 and 30 mg/kg for the M1/M2-AUGplus (SEQ ID NO: 13; AVI-7100) and 0.5 and 1.5 mg/kg for the M1/M2-AUG PPMO (SEQ ID NO: 12) conjugated on the 3′ end to SEQ ID NO:124). Dosing was performed four hours prior to infection and on Days 1, 3 and 5. Tamiflu (Oseltamivir) was administered (10 mg/kg dose) as a positive antiviral control in parallel with the antisense compounds. Saline was also included as a negative control.

In-life observations included weight gain (FIG. 7A), sneezing (FIG. 7B), nasal discharge (FIG. 7C) and respiratory distress (FIG. 7D). The M1/M2-AUG targeted compounds prevented weight loss and reduced sneezing, nasal discharge and respiratory distress. Viral titers from nasal washes for Day 1 through Day 5 post-infection are shown in FIG. 7E as area under the curve (AUC) tissue culture infectious dose (TCID). The M1/M2-AUG PPMO agent showed a 2.3 log reduction relative to saline (99.6% reduction) and a 1.1 log reduction greater than Tamiflu (94.4% greater).

To further evaluate the efficacy of AVI-7100 (SEQ ID NO:13), a PMOplus targeted to the influenza M1/M2 segment translation start site was tested in ferrets infected with a non-adapted oseltamivir-resistant H1N1 (SOIV) pandemic influenza virus. A total of 36 male ferrets were utilized in this study. Male ferrets with matched body weight of about 700 g at study initiation were randomized to one of 5 treatment groups (shown in Table 7 below), and housed in Hepa filtered cages (four per cage) to minimize cage to cage transmission of virus. The cages were maintained within the Tulane University Medical Center BSL-2 laboratory.

TABLE 7 Ferret Study Design Dose Sacrifice Group Agent Chemistry (mg/kg) Route Schedule Day 7 1 Tamiflu — 5 p.o. −4 H, 12, 24, 36, 48, 60, 8 72, 84, 96, 108, 120 H 2 M1/M2 PMOplus 30 i.p. −4 H, 1, 2, 3, 4, 5 D 8 3 M1/M2 PMOplus 10 i.p. −4 H, 1, 2, 3, 4, 5 D 8 4 Saline — 0.5 i.n. −4 H, 1, 2, 3, 4, 5 D 6 5 M1/M2 and PMOplus 10 i.p. −4 H, 1, 2, 3, 4, 5 D 6 Tamiflu — 5 p.o. −4 H, 12, 24, 36, 48, 60, 72, 84, 96, 108, 120 H TOTALS 36

The ferrets were treated with AVI-7100 1 to 4 hours prior to viral challenge. The route of administration was intraperitoneal for groups 2, 3 and 5; and oral for group 1. The dose interval was at −4 hours, 24, 48, 72, 96 and 120 hours post viral challenge. The 5 groups were treated as follows: Group 1 received oseltamivir at 5 mg/kg every 12 hours by the oral route, Group 2 received AVI-7100 (a PMOplus compound; 5′-CGG T+TA GAA GAC+TCA TC+T TT-3′) at 10 mg/kg dose by the i.p. route, Group 3 received AVI-7100 (a PMOplus compound) at 30 mg/kg dose by the i.p. route, Group 4 received a sterile saline control by the i.p. route, Group 5 received AVI-7100 at 10 mg/kg once a day by the i.p. route and oseltamivir at 5 mg/kg twice a day. The reason for the differences in group sizes between groups 1-2 (8 ferrets each) and groups 4-5 (6 ferrets each) was due to the limited availability of influenza A seronegative ferrets at the time of the study initiation.

All of the ferrets involved in this study survived to the end of the study, day eight post infection, suggesting either that these animals were very healthy, or that this particular virus was not very pathogenic in this model. Nonetheless, as shown below, these results not only show that treatment with AVI-7100 significantly reduces symptoms of influenza virus infection relative to untreated or oseltamivir-treated controls, but also illustrate the synergistic effects that can be achieved with the combination of AVI-7100 and oseltamivir. A summary of the clinical observations is shown in Table 8 below.

TABLE 8 Clinical Observations Clinical Body Weight Change (g/day) Max Body Temperatures (° F.) Group Scores Pre Post Difference Pre Post Difference Tamiflu 1.17 ± 0.25 15.1 ± 0.4  8.5 ± 3.2 −6.1 104.4 105.7 +1.3 M1-30 1.00 ± 0.00 11.8 ± 0.8 12.6 ± 2.0 +0.8 104.7 104.2 −0.5 M1-10 1.11 ± 0.21 16.6 ± 0.8 10.9 ± 1.5 −5.7 105.4 106.1 +0.7 Saline 1.19 ± 0.25 14.3 ± 0.6 11.4 ± 2.1 −2.9 105.9 106.2 +0.3 M1 + Tamiflu 1.06 ± 0.06 14.4 ± 0.6 14.9 ± 1.0 +0.5 105.0 104.9 −0.1

As a further indicator, observations of cells that infiltrate into the upper respiratory tract are a measure of the severity of the infection. The summary of macrophage cellularity in nasal wash is included in Table 9 below. In addition, untreated and oseltamivir-only treated ferrets showed significant congestion in the lung with marked alveolitis (inflammation of the lung), abundant infiltrating cells including lymphocytes and neutrophils, and moderate alveolar wall thickening of the lung. In contrast, AVI-7100 treated ferrets (with or without oseltamivir) showed no congestion in the lung, only mild alveolitis, and few infiltrating cells.

TABLE 9 Macrophage Cellularity in Upper Respiratory Tract Average ± Std Group Deviation Day 3 Peak Tamiflu 2.98 ± 2.71 7.91 ± 7.28 M1-30 2.78 ± 2.97 1.59 ± 1.28 M1-10 4.34 ± 3.82 3.88 ± 4.73 Saline 5.02 ± 3.77 2.41 ± 3.24 M1 + Tamiflu 4.27 ± 3.10 0.91 ± 1.25

As shown in Table 10 below, peak viremia in nasal wash was observed on day 1. No nasal wash was collected on day 2, 4, 6 and 7 in order to minimize the untoward influence of collecting the nasal wash on the progression of the viral infection. Significant benefit was observed in the AVI-7100 treated group relative to either saline or oseltamivir. Synergistic effects were also observed with the combination of AVI-7100 (10 mg/kg) and oseltamivir, relative to AVI-7100-only (10 mg/kg) and oseltamivir-only treatments. Here, the AUC for viral titer in nasal wash for the combination (AVI-7100 and oseltamivir) shows a greater than 4 log reduction relative to the tamiflu-only group and a greater than 3 log reduction relative to the saline group. The combination also shows a much greater reduction in viral titer relative to the equivalent amount of AVI-7100 alone (from AUC of 5.515 to AUC of 2.999), suggesting that AVI-7100 may enhance the anti-viral effects of oseltamivir. This result is surprising because the virus used in this study is otherwise resistant to oseltamivir.

TABLE 10 Viral Titer AVI-7100 AVI-7100 Oseltamivir + Oseltamivir 30 mg/kg 10 mg/kg AVI-7100 Day (n = 8) (n = 8) (n = 8) Saline (n = 6) 10 mg/kg (n = 6) 1 2.42 ± 0.58 0.57 ± 0.49 1.10 ± 1.11 2.42 ± 0.49 0.82 ± 0.79 3 0.77 ± 0.73 0.81 ± 0.25 1.19 ± 0.80 0.75 ± 0.27 0.69 ± 0.65 5 0.67 ± 0.67 1.13 ± 0.58 0.25 ± 0.38 0.67 ± 0.41 0.13 ± 0.25 8 0.92 ± 0.37 0.44 ± 0.42 0.94 ± 0.82 0.33 ± 0.61 0.31 ± 0.37 AUC 7.015 5.675 5.515 6.090 2.990

Example 3 Inhibition of Influenza a Virus in Tissue Culture Using Splice Site-Targeted Antisense Oligomers

An aspect of the present invention is the inhibition of influenza A virus replication by antisense targeting of multiple sites within the M1/M2 segment. In addition to inhibition of translation by targeting the common M1/M2 AUG start site, splice donor and splice acceptor sites can also be targeted using compounds of the invention. Two PMO that target the splice acceptor site at position 740 were synthesized as peptide conjugated PPMO, SA740 and SA746 (SEQ ID NOs: 26 and 29, respectively) and placed into an in vitro tissue culture replication system for H1N1 strain PR8. The P007 cell penetrating peptide (SEQ ID NO: 118) was conjugated to the 3′ terminus of the PMO.

An alveolar murine macrophage cell line (ATCC; AMJ2-C11) was infected at 0.1 MOI with H1N1 (strain PR8) and 1 hour post-infection PPMOs were added. Cells were incubated at 35 degrees C. overnight. Viral supernatant was then taken and incubated with VNAR protease to release viral RNA. HA RNA was quantified by quantitative real-time PCR (qRT-PCR). Cells were washed, fixed, and permeabilized. M1 and M2 proteins were then probed with monoclonal antibodies for 30 min at 37 degrees C. Cells were washed and anti-mouse IgG conjugated with Alexa 646 was added for 15 min at room temperature. M1 and M2 were then assayed by flow cytometry. To determine M1 and M2 protein levels, the percent of M1 or M2 positive cells was multiplied by the mean fluorescent intensity of M1 or M2. Each sample was then divided by the untreated control to generate the percent of M1 or M2 compared to untreated scramble controls.

FIG. 8A shows the reduction in viral HA RNA levels (measured using qRT-PCR). Both SA740 and SA746 inhibited HA RNA production indicating an inhibition of viral replication compared to the scramble control. The most profound effect was observed at 10 micromolar with an approximate two-log reduction using SA746 and one-log reduction with SA740. FIGS. 8B and 8C show the effect of SA740 and SA746 on M1 and M2 protein levels, respectively. The flow cytometry method described above was used to determine relative protein levels. Both oligomers inhibited the production of the M2 protein whereas M1 protein levels were reduced by SA740.

Example 4 Inhibition of Influenza a Virus in Tissue Culture Using Locked Nucleic Acid Oligomers

The compounds of the present invention include oligonucleotide analogs comprised of different chemical entities than PMO. A series of locked nucleic acids that target the M1/M2 segment AUG start site region were synthesized (LNA-AUG1, LNA-AUG12, LNA-AUG13 and LNA-AUG10; SEQ ID NOs: 63, 74, 75 and 72, respectively) and tested in the same assay for viral RNA and M2 protein expression as described above in Example 3. Intracellular delivery of the LNA oligomers was by way of gymnotic delivery (Stein, Hansen et al. 2010). AMJ2-C11 cells were infected with PR8 for 1 h and then washed. The cells were then plated in a 96 well plate with LNA or 2′OMe compounds and allowed to incubate overnight at 35 degrees C. Viral RNA levels and M2 protein expression were assessed at that time (approximately 18 hours total incubation time). FIG. 9A shows the effect of the four different LNAs on viral RNA levels (the HA segment). At 7.5 micromolar there was an approximately 3-log reduction in viral HA RNA levels for the LNA-AUG1 oligomer compared to an approximately 1.5 log reduction for the LNA-AUG12 compound (SEQ ID NOs: 63 and 74, respectively). LNA-AUG1 is a 20mer whereas LNA-AUG12 is a 16mer. There is a rank order of effectiveness according to length for all four LNA oligomers indicating the longer LNAs are preferred embodiments of the invention. This relationship is also observed in the measurement of M2 protein expression shown in FIG. 9B with the LNA-AUG1 oligo being most effective at compared to the LNA-AUG10 compound at 7.5 micromolar (SEQ ID NOs: 63 and 72, respectively). The relatively short LNA-AUG10 compound consisting of a 10 base targeting sequence was the least effective in both the viral HA RNA and M2 protein expression assays.

Example 5 Inhibition of Influenza a Virus in Tissue Culture Using 2′OMe Oligomers

The compounds of the present invention also include antisense analog oligomers consisting of 2′OMe residues linked by phosphorothioate linkages. Three 2′OMe oligos were produced by IDT, 2′OMe-AUG1, 2′OMe-AUG2 and 2′OMe-SA1; SEQ ID NOs: 12, 20 and 26, respectively. These oligomers were designed to target either the AUG start codon of the M1/M2 segment or the splice acceptor site located at nucleotide 740. The 2′OMe-SA1 sequence (SEQ ID NO: 26) matches that of the PPMO compound described in Example 3 above as SA740. The 2′OMe compounds were tested in the same assay for their ability to inhibit viral HA RNA levels and M2 protein expression as described above in Examples 3 and 4. Intracellular delivery was attained through gymnosis as described above for LNAs in Example 4.

All three 2′OMe compounds were effective at reducing viral HA RNA levels from between 2.5 and 4.5 logs at 7.5 micromolar as shown in FIG. 10A. The relative effectiveness of the three compounds was also observed in the M2 protein measurement assays as shown in FIG. 10B. The most effective compound was the 2′OMe-AUG2 24mer that targets the AUG start site region (SEQ ID NO:20). Similarly effective was the 2′OMe-SA1 oligomer (SEQ ID NO:26) that targets the downstream M1/M2 splice acceptor site.

Example 6 Inhibition of M1 and M2 Protein Expression In Vitro

The effect of an exemplary compound of the invention on M1 and M2 protein expression was evaluated using a western blot analysis of treated and infected AMJ2-C11 cells. An exemplary PPMO compound of the invention (M1/M2 PPMO; P007-M1/M2-AUG; SEQ ID NO: 12 conjugated at the 3′ end to SEQ ID NO: 118) was used to treat MDCK cells overnight at 3 micromolar. The cells were then subsequently infected with H1N1-PR8 at 0.01 MOI for 1 hour and washed. 18 hours post-infection the cells were lysed and protein extracted. Equal amounts of protein were loaded onto gels for subsequent analysis by a standard immunoblot (western) assay using monoclonal antibodies that react with the M1, M2 and actin proteins. As shown in FIG. 11, the expression of both M1 and M2 proteins was reduced compared to an untreated control and an irrelevant control PPMO (Dengue). Analysis of the signal intensity indicated that M2 protein expression was inhibited by the M1/M2 PPMO to a greater extent than M1 protein expression as shown in FIG. 11 (i.e., 9% for M2 versus 27% for M1). The signal comparison for M1 and M2 were normalized to the actin control.

Sequence Listing SEQ ID NO Target Sequences (5′ to 3′) AGCAAAAGCAGGUAGAUAUUUAAAGAUGAGUCUUCUAACCGAGGUCGAAACGUACGUUCU 1 AAGCAGGUAGAUAUUUAAAGAUGAGUCUUCUAACCGAGGUCGAAA 2 AGCAAAAGCAGGUAGAUAUUUAAAG 3 CUUUAAAUAUCUACCUGCUUUUGCU 4 AGCGAAAGCAGGUAGAUAUUGAAAGAUGAGUCUUCUAACCGAGGUCGAAACGUACGUUCU 5 AGCAAAAGCAGGUAGAUAUUGAAAGAUGAGUCUUCUAACCGAGGUCGAAACGUACGUUCU 6 AGCAAAAGCAGGUAGAUAUUGAAAGAUGAGCCUUCUAACCGAGGUCGAAACGUAUGUUCU 7 AGCAAAAGCAGGUAGAUAUUGAAAGAUGAGUCUUCUAACCGAGGUCGAAACGUACGUUCU 8 AAAUUUGCAGGCCUACCAGAAACGAAUGGGAGUGCAGAUGCAGCGAUUCAA 9 AAAUUUGCAGGCCUACCAGAAGCGAAUGGGAGUGCAGAUGCAGCGAUUCAA 10 AGCGAAAGCAGGTAGATATTGAAAGATGAGTCTTCTAACCGAGGTCGAAACGTACGTTCTC 11 TCTATCATCCCGTCAGGCCCCCTCAAAGCCGAGATCGCACAGAGACTTGAAGATGTCTTTG CAGGGAAGAACACCGATCTTGAGGTTCTCATGGAATGGCTAAAGACAAGACCAATCCTGTC ACCTCTGACTAAGGGGATTTTAGGATTTGTGTTCACGCTCACCGTGCCCAGTGAGCGAGGA CTGCAGCGTAGACGCTTTGTCCAAAATGCCCTTAATGGGAACGGGGATCCAAATAACATGG ACAAAGCAGTTAAACTGTATAGGAAGCTCAAGAGGGAGATAACATTCCATGGGGCCAAAGA AATCTCACTCAGTTATTCTGCTGGTGCACTTGCCAGTTGTATGGGCCTCATATACAACAGG ATGGGGGCTGTGACCACTGAAGTGGCATTTGGCCTGGTATGTGCAACCTGTGAACAGATTG CTGACTCCCAGCATCGGTCTCATAGGCAAATGGTGACAACAACCAACCCACTAATCAGACA TGAGAACAGAATGGTTTTAGCCAGCACTACAGCTAAGGCTATGGAGCAAATGGCTGGATCG AGTGAGCAAGCAGCAGAGGCCATGGAGGTTGCTAGTCAGGCTAGGCAAATGGTGCAAGCGA TGAGAACCATTGGGACTCATCCTAGCTCCAGTGCTGGTCTGAAAAATGATCTTCTTGAAAA TTTGCAGGCCTATCAGAAACGAATGGGGGTGCAGATGCAACGGTTCAAGTGATCCTCTCGC TATTGCCGCAAATATCATTGGGATCTTGCACTTGATATTGTGGATTCTTGATCGTCTTTTT TTCAAATGCATTTACCGTCGCTTTAAATACGGACTGAAAGGAGGGCCTTCTACGGAAGGAG TGCCAAAGTCTATGAGGGAAGAATATCGAAAGGAACAGCAGAGTGCTGTGGATGCTGACGA TGGTCATTTTGTCAGCATAGAGCTGGAGTAAAAAACTACCTTGTTTCTACT Oligomer Targeting Sequences (5′ to 3′) CGGTTAGAAGACTCATCTTT 12 CGGT+TAGAAGAC+TCATC+TTT 13 AGAAGACTCATCTTTCAATA 14 TTAGAAGACTCATCTTTCAA 15 CTCGGTTAGAAGACTCATCT 16 ATCTTTCAATATCTACCTGCTTTTG 17 CTCATCTTTCAATATCTACCTGCTT 18 CTCGGTTAGAAGACTCATCTTTCAA 19 ACCTCGGTTAGAAGACTCATCTTTC 20 TCGACCTCGGTTAGAAGACTCATCT 21 TTTCGACCTCGGTTAGAAGACTCAT 22 AGCAAAAGCAGGTAGATATTGAAAA 23 AGCAGGTAGATATTGAAAAATGAGT 24 CTCCCATTCGCTTCTGGTAGGCCT 25 CACTCCCATTCGCTTCTGGTAGGC 26 TGCACTCCCATTCGCTTCTGGTAG 27 TCTGCACTCCCATTCGCTTCTGGT 28 CATCTGCACTCCCATTCGCTTCTG 29 AGCAAAAGCAGIGTAGATAATC 30 AGCAAAAGCAGIG+TAGA+TAA+TC 31 CGGATTGACATCCATTCAAATG 32 CGGAT+TGACA+TCCAT+TCAAATG 33 CTT+TCAA+TATCTACC+TGCTT 34 C+TCA+TCTTTCAA+TATCTACC 35 AC+TCA+TCTTTCAA+TATCTAC 36 GAC+TCA+TCTTTCAA+TATCTA 37 AGAC+TCA+TCTTTCAA+TATCT 38 AAGAC+TCA+TCTTTCAA+TATC 39 GAAGAC+TCA+TCTTTCAA+TAT 40 AGAAGAC+TCA+TCTTTCAA+TA 41 TAGAAGAC+TCA+TCTTTCAA+T 42 T+TAGAAGAC+TCA+TCTTTCAA 43 GT+TAGAAGAC+TCA+TCTTTCA 44 TCGGT+TAGAAGAC+TCA+TCTT 45 CCTCGGT+TAGAAGAC+TCA+TC 46 GACC+TCGGT+TAGAAGAC+TCA 47 PNA Targeting Sequences CGGTTAGAAGACTCATCTTT 48 CGGTTAGAAGACTCATCT 49 CGGTTAGAAGACTCAT 50 AGAAGACTCATCTTTCAATA 51 TTAGAAGACTCATCTTTCAA 52 CTCGGTTAGAAGACTCATCT 53 TCAATATCTACCTGCTTTTG 54 CTTTCAATATCTACCTGCTT 55 AGCAAAAGCAGGTAGATATT 56 AGCAGGTAGATATTGAAAAA 57 CATTCGCTTCTGGTAGGCCT 58 CCCATTCGCTTCTGGTAGGC 59 CTCCCATTCGCTTCTGGTAG 60 CACTCCCATTCGCTTCTGGT 61 TGCACTCCCATTCGCTTCTG 62 LNA Targeting Sequences CgGtTaGaAgAcTcAtCtTt 63 GaAgAcTcAt 64 GAaGaCtCAT 65 GAAGACTCAT 66 AGAAGACTCA 67 TAGAAGACTC 68 TTAGAAGACT 69 AAGACTCATC 70 AGACTCATCT 71 GACTCATCTT 72 ACTCATCTTT 73 CgGtTaGaAgAcTcAt 74 GtTaGaAgAcTcAt 75 GTTAGAAGACT 76 CATCTTTAAAT 77 CaTcTtTaAaTaTcTaC 78 CGGTTAGAAGACTCAT 79 GGTTAGAAGACTCATC 80 GTTAGAAGACTCATCT 81 TTAGAAGACTCATCTT 82 TAGAAGACTCATCTTT 83 AGAAGACTCATCTTTA 84 GAAGACTCATCTTTAA 85 AAGACTCATCTTTAAA 86 AGACTCATCTTTAAAT 87 GACTCATCTTTAAATA 88 ACTCATCTTTAAATAT 89 CTCATCTTTAAATATC 90 TCATCTTTAAATATCT 91 CATCTTTAAATATCTA 92 ATCTTTAAATATCTAC 93 TCTTTAAATATCTACC 94 CTTTAAATATCTACCA 95 TTTAAATATCTACCAG 96 CgGgTaGaAgAcTcAt 97 GgTtAgAaGaCtCaTc 98 GtTaGaAgAcTcAtCt 99 TtAgAaGaCtCaTcTt 100 TaGaAgAcTcAtCtTt 101 AgAaGaCtCaTcTtTa 102 GaAgAcTcAtCtTtAa 103 AaGaCtCaTcTtTaAa 104 AgAcTcAtCtTtAaAt 105 GaCtCaTcTtTaAaTa 106 AcTcAtCtTtAaAtAt 107 CtCaTcTaTaAaTaTc 108 TcAtCtTtAaAtAtCt 109 CaTcTtTaAaTaTcTa 110 AtCtTtAaAtAtCtAc 111 TcTtTaAaTaTcTaCc 112 CtTtAaAtAtCtAcCa 113 TtTaAaTaTcTaCcAg 114 Peptide Sequences RRRQRRKKRC 115 RRRRRRRRRFFC 116 RRRRRFFRRRRC 117 RAhxRRAhxRRAhxRRAhxRAhxB 118 RRRRRRRRC 119 RRRRRRRRRC 120 RRRRRRRRG 121 RRRRRRRRRG 122 RAhxRRAhxRRAhxRRAhxRRAhxRAhxB 123 RAhxRRBRRAhxRRBRAhxB 124 RARRARRARRARFFC 125 RGRRGRRGRRGRFFC 126 RRRRRRRRRFFG 127 RRRRRRRRRFFAhxB 128 

It is claimed:
 1. An isolated antiviral antisense oligonucleotide, comprising a) a nuclease-resistant backbone; b) 12-40 nucleotide bases, and c) a targeting sequence of at least 10 bases in length that hybridizes to a target region selected from the 45 bases surrounding the AUG start codon of an influenza viral M1 or M2 mRNA; wherein the oligonucleotide (i) comprises morpholino subunits linked by substantially uncharged, phosphorous-containing intersubunit linkages that join a morpholino nitrogen of one subunit to a 5′ exocyclic carbon of an adjacent subunit; (ii) comprises one or more locked nucleic acid subunits; (iii) comprises 2′OMe residues; or (iv) is a peptide nucleic acid; wherein the oligonucleotide comprises a base sequence selected from the group consisting of: SEQ ID NOS:12-16, 19-22, 34 and 45-47.
 2. The oligonucleotide of claim 1, wherein the morpholino subunits are joined by phosphorodiamidate linkages in accordance with the structure:

where Y₁═O, Z═O, Pj is a purine or pyrimidine base-pairing moiety effective to bind, by base-specific hydrogen bonding, to a base in a polynucleotide, and X is alkyl, alkoxy, thioalkoxy, or alkyl amino.
 3. The oligonucleotide of claim 2, wherein X is 1-piperazine for at least 2 and no more than half of the total number of intersubunit linkages, and where the uncharged linkages are X≡NR₂, wherein each R is independently hydrogen or methyl.
 4. The oligonucleotide of claim 1, wherein the oligonucleotide comprises SEQ ID NO:12, 13, 20, 34, 45, 46, or
 47. 5. The oligonucleotide of claim 1, wherein the oligonucleotide is conjugated to an arginine-rich polypeptide that enhances the uptake of the oligonucleotide into host cells.
 6. A method of reducing replication of influenza virus, comprising contacting an influenza virus infected cell with an antiviral antisense oligonucleotide of claim
 1. 7. The oligonucleotide of claim 1, wherein the oligonucleotide is characterized by the ability to form a heteroduplex structure with the viral target region, wherein said heteroduplex structure is: a) composed of the positive sense strand of the virus and the oligonucleotide, and b) characterized by a Tm of dissociation of at least 45° C.
 8. The oligonucleotide of claim 5, wherein the arginine-rich polypeptide is selected from the group consisting of SEQ ID NOS:115-128.
 9. The oligonucleotide of claim 1, wherein the oligonucleotide consists essentially of locked nucleic acid subunits.
 10. The method of claim 6, wherein the cell is in a subject, and the method comprises administering the antisense oligonucleotide to the subject.
 11. The method of claim 10, wherein the subject has a secondary bacterial infection, further comprising administering a bacterial antibiotic, separately or concurrently in combination with the antiviral antisense oligonucleotide.
 12. The method of claim 11, wherein the secondary bacterial infection is a Streptococcal pneumonia infection.
 13. The method of claim 11, wherein the antibiotic is a beta-lactam.
 14. The method of claim 11, wherein the antibiotic is selected from penicillin, amoxicillin, cephalosporins, chloramphenicol, and clindamycin.
 15. The method of claim 10, further comprising administering an antisense oligonucleotide targeted against an RNA molecule encoding CD200 or the CD200 receptor, separately or concurrently in combination with the antiviral antisense oligonucleotide.
 16. A pharmaceutical composition comprising an antisense oligonucleotide of claim 1, and a pharmaceutically acceptable carrier.
 17. The pharmaceutical composition of claim 16, further comprising a bacterial antibiotic.
 18. The pharmaceutical composition of claim 16, further comprising an antisense oligonucleotide targeted against an RNA molecule encoding CD200 or the CD200 receptor. 